Merge pull request #5200

c1c9d5b [Qt] Add Smartfee to GUI (Cozz Lovan)
e7876b2 [Wallet] Prevent user from paying a non-sense fee (Cozz Lovan)
ed3e5e4 [Wallet] Add global boolean whether to pay at least the custom fee (default=true) (Cozz Lovan)
0ed9675 [Wallet] Add global boolean whether to send free transactions (default=true) (Cozz Lovan)

21 files changed, 911 insertions, 164 deletions

diff --git a/src/init.cpp b/src/init.cpp
index b290d54158..4a9982a1cd 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -290,6 +290,7 @@ std::string HelpMessage(HelpMessageMode mode)
     strUsage += "  -paytxfee=<amt>        " + strprintf(_("Fee (in BTC/kB) to add to transactions you send (default: %s)"), FormatMoney(payTxFee.GetFeePerK())) + "\n";
     strUsage += "  -rescan                " + _("Rescan the block chain for missing wallet transactions") + " " + _("on startup") + "\n";
     strUsage += "  -salvagewallet         " + _("Attempt to recover private keys from a corrupt wallet.dat") + " " + _("on startup") + "\n";
+    strUsage += "  -sendfreetransactions  " + strprintf(_("Send transactions as zero-fee transactions if possible (default: %u)"), 0) + "\n";
     strUsage += "  -spendzeroconfchange   " + strprintf(_("Spend unconfirmed change when sending transactions (default: %u)"), 1) + "\n";
     strUsage += "  -txconfirmtarget=<n>   " + strprintf(_("If paytxfee is not set, include enough fee so transactions are confirmed on average within n blocks (default: %u)"), 1) + "\n";
     strUsage += "  -upgradewallet         " + _("Upgrade wallet to latest format") + " " + _("on startup") + "\n";
@@ -704,6 +705,7 @@ bool AppInit2(boost::thread_group& threadGroup)
     }
     nTxConfirmTarget = GetArg("-txconfirmtarget", 1);
     bSpendZeroConfChange = GetArg("-spendzeroconfchange", true);
+    fSendFreeTransactions = GetArg("-sendfreetransactions", false);
 
     std::string strWalletFile = GetArg("-wallet", "wallet.dat");
 #endif // ENABLE_WALLET
diff --git a/src/qt/bitcoinamountfield.cpp b/src/qt/bitcoinamountfield.cpp
index 2c100337d2..5b8ab23b26 100644
--- a/src/qt/bitcoinamountfield.cpp
+++ b/src/qt/bitcoinamountfield.cpp
@@ -221,6 +221,12 @@ void BitcoinAmountField::clear()
     unit->setCurrentIndex(0);
 }
 
+void BitcoinAmountField::setEnabled(bool fEnabled)
+{
+    amount->setEnabled(fEnabled);
+    unit->setEnabled(fEnabled);
+}
+
 bool BitcoinAmountField::validate()
 {
     bool valid = false;
diff --git a/src/qt/bitcoinamountfield.h b/src/qt/bitcoinamountfield.h
index 4ab66001f0..1bad8ce1b8 100644
--- a/src/qt/bitcoinamountfield.h
+++ b/src/qt/bitcoinamountfield.h
@@ -48,6 +48,9 @@ public:
     /** Make field empty and ready for new input. */
     void clear();
 
+    /** Enable/Disable. */
+    void setEnabled(bool fEnabled);
+
     /** Qt messes up the tab chain by default in some cases (issue https://bugreports.qt-project.org/browse/QTBUG-10907),
         in these cases we have to set it up manually.
     */
diff --git a/src/qt/coincontroldialog.cpp b/src/qt/coincontroldialog.cpp
index ba0febe546..85b43b7b1f 100644
--- a/src/qt/coincontroldialog.cpp
+++ b/src/qt/coincontroldialog.cpp
@@ -24,6 +24,7 @@
 #include <QDialogButtonBox>
 #include <QFlags>
 #include <QIcon>
+#include <QSettings>
 #include <QString>
 #include <QTreeWidget>
 #include <QTreeWidgetItem>
@@ -130,10 +131,22 @@ CoinControlDialog::CoinControlDialog(QWidget *parent) :
 
     // default view is sorted by amount desc
     sortView(COLUMN_AMOUNT_INT64, Qt::DescendingOrder);
+
+    // restore list mode and sortorder as a convenience feature
+    QSettings settings;
+    if (settings.contains("nCoinControlMode") && !settings.value("nCoinControlMode").toBool())
+        ui->radioTreeMode->click();
+    if (settings.contains("nCoinControlSortColumn") && settings.contains("nCoinControlSortOrder"))
+        sortView(settings.value("nCoinControlSortColumn").toInt(), ((Qt::SortOrder)settings.value("nCoinControlSortOrder").toInt()));
 }
 
 CoinControlDialog::~CoinControlDialog()
 {
+    QSettings settings;
+    settings.setValue("nCoinControlMode", ui->radioListMode->isChecked());
+    settings.setValue("nCoinControlSortColumn", sortColumn);
+    settings.setValue("nCoinControlSortOrder", (int)sortOrder);
+
     delete ui;
 }
 
@@ -290,19 +303,19 @@ void CoinControlDialog::clipboardAmount()
 // copy label "Fee" to clipboard
 void CoinControlDialog::clipboardFee()
 {
-    GUIUtil::setClipboard(ui->labelCoinControlFee->text().left(ui->labelCoinControlFee->text().indexOf(" ")));
+    GUIUtil::setClipboard(ui->labelCoinControlFee->text().left(ui->labelCoinControlFee->text().indexOf(" ")).replace("~", ""));
 }
 
 // copy label "After fee" to clipboard
 void CoinControlDialog::clipboardAfterFee()
 {
-    GUIUtil::setClipboard(ui->labelCoinControlAfterFee->text().left(ui->labelCoinControlAfterFee->text().indexOf(" ")));
+    GUIUtil::setClipboard(ui->labelCoinControlAfterFee->text().left(ui->labelCoinControlAfterFee->text().indexOf(" ")).replace("~", ""));
 }
 
 // copy label "Bytes" to clipboard
 void CoinControlDialog::clipboardBytes()
 {
-    GUIUtil::setClipboard(ui->labelCoinControlBytes->text());
+    GUIUtil::setClipboard(ui->labelCoinControlBytes->text().replace("~", ""));
 }
 
 // copy label "Priority" to clipboard
@@ -320,7 +333,7 @@ void CoinControlDialog::clipboardLowOutput()
 // copy label "Change" to clipboard
 void CoinControlDialog::clipboardChange()
 {
-    GUIUtil::setClipboard(ui->labelCoinControlChange->text().left(ui->labelCoinControlChange->text().indexOf(" ")));
+    GUIUtil::setClipboard(ui->labelCoinControlChange->text().left(ui->labelCoinControlChange->text().indexOf(" ")).replace("~", ""));
 }
 
 // treeview: sort
@@ -402,26 +415,22 @@ void CoinControlDialog::viewItemChanged(QTreeWidgetItem* item, int column)
 }
 
 // return human readable label for priority number
-QString CoinControlDialog::getPriorityLabel(const CTxMemPool& pool, double dPriority)
+QString CoinControlDialog::getPriorityLabel(double dPriority, double mempoolEstimatePriority)
 {
-    // confirmations -> textual description
-    typedef std::map<unsigned int, QString> PriorityDescription;
-    const static PriorityDescription priorityDescriptions = boost::assign::map_list_of
-        (1, tr("highest"))(2, tr("higher"))(3, tr("high"))
-        (5, tr("medium-high"))(6, tr("medium"))
-        (10, tr("low-medium"))(15, tr("low"))
-        (20, tr("lower"));
-
-    BOOST_FOREACH(const PriorityDescription::value_type& i, priorityDescriptions)
-    {
-        double p = mempool.estimatePriority(i.first);
-        if (p > 0 && dPriority >= p) return i.second;
-    }
-    // Note: if mempool hasn't accumulated enough history (estimatePriority
-    // returns -1) we're conservative and classify as "lowest"
-    if (mempool.estimatePriority(nTxConfirmTarget) <= 0 && AllowFree(dPriority))
-        return ">=" + tr("medium");
-    return tr("lowest");
+    double dPriorityMedium = mempoolEstimatePriority;
+
+    if (dPriorityMedium <= 0)
+        dPriorityMedium = AllowFreeThreshold(); // not enough data, back to hard-coded
+
+    if      (dPriority / 1000000 > dPriorityMedium) return tr("highest");
+    else if (dPriority / 100000 > dPriorityMedium)  return tr("higher");
+    else if (dPriority / 10000 > dPriorityMedium)   return tr("high");
+    else if (dPriority / 1000 > dPriorityMedium)    return tr("medium-high");
+    else if (dPriority > dPriorityMedium)           return tr("medium");
+    else if (dPriority * 10 > dPriorityMedium)      return tr("low-medium");
+    else if (dPriority * 100 > dPriorityMedium)     return tr("low");
+    else if (dPriority * 1000 > dPriorityMedium)    return tr("lower");
+    else                                            return tr("lowest");
 }
 
 // shows count of locked unspent outputs
@@ -470,6 +479,7 @@ void CoinControlDialog::updateLabels(WalletModel *model, QDialog* dialog)
     double dPriorityInputs      = 0;
     unsigned int nQuantity      = 0;
     int nQuantityUncompressed   = 0;
+    bool fAllowFree             = false;
 
     vector<COutPoint> vCoinControl;
     vector<COutput>   vOutputs;
@@ -522,24 +532,22 @@ void CoinControlDialog::updateLabels(WalletModel *model, QDialog* dialog)
         nBytes = nBytesInputs + ((CoinControlDialog::payAmounts.size() > 0 ? CoinControlDialog::payAmounts.size() + 1 : 2) * 34) + 10; // always assume +1 output for change here
 
         // Priority
+        double mempoolEstimatePriority = mempool.estimatePriority(nTxConfirmTarget);
         dPriority = dPriorityInputs / (nBytes - nBytesInputs + (nQuantityUncompressed * 29)); // 29 = 180 - 151 (uncompressed public keys are over the limit. max 151 bytes of the input are ignored for priority)
-        sPriorityLabel = CoinControlDialog::getPriorityLabel(mempool, dPriority);
+        sPriorityLabel = CoinControlDialog::getPriorityLabel(dPriority, mempoolEstimatePriority);
 
-        // Voluntary Fee
-        nPayFee = payTxFee.GetFee(max((unsigned int)1000, nBytes));
+        // Fee
+        nPayFee = CWallet::GetMinimumFee(nBytes, nTxConfirmTarget, mempool);
 
-        // Min Fee
-        if (nPayFee == 0)
-        {
-            nPayFee = CWallet::GetMinimumFee(nBytes, nTxConfirmTarget, mempool);
-
-            double dPriorityNeeded = mempool.estimatePriority(nTxConfirmTarget);
-            if (dPriorityNeeded <= 0 && !AllowFree(dPriority)) // not enough mempool history: never send free
-                dPriorityNeeded = std::numeric_limits<double>::max();
+        // Allow free?
+        double dPriorityNeeded = mempoolEstimatePriority;
+        if (dPriorityNeeded <= 0)
+            dPriorityNeeded = AllowFreeThreshold(); // not enough data, back to hard-coded
+        fAllowFree = (dPriority >= dPriorityNeeded);
 
-            if (nBytes <= MAX_FREE_TRANSACTION_CREATE_SIZE && dPriority >= dPriorityNeeded)
+        if (fSendFreeTransactions)
+            if (fAllowFree && nBytes <= MAX_FREE_TRANSACTION_CREATE_SIZE)
                 nPayFee = 0;
-        }
 
         if (nPayAmount > 0)
         {
@@ -595,7 +603,7 @@ void CoinControlDialog::updateLabels(WalletModel *model, QDialog* dialog)
     l6->setText(sPriorityLabel);                                             // Priority
     l7->setText(fDust ? tr("yes") : tr("no"));                               // Dust
     l8->setText(BitcoinUnits::formatWithUnit(nDisplayUnit, nChange));        // Change
-    if (nPayFee > 0)
+    if (nPayFee > 0 && !(payTxFee.GetFeePerK() > 0 && fPayAtLeastCustomFee && nBytes < 1000))
     {
         l3->setText("~" + l3->text());
         l4->setText("~" + l4->text());
@@ -605,7 +613,7 @@ void CoinControlDialog::updateLabels(WalletModel *model, QDialog* dialog)
 
     // turn labels "red"
     l5->setStyleSheet((nBytes >= MAX_FREE_TRANSACTION_CREATE_SIZE) ? "color:red;" : "");// Bytes >= 1000
-    l6->setStyleSheet((dPriority > 0 && !AllowFree(dPriority)) ? "color:red;" : "");    // Priority < "medium"
+    l6->setStyleSheet((dPriority > 0 && !fAllowFree) ? "color:red;" : "");              // Priority < "medium"
     l7->setStyleSheet((fDust) ? "color:red;" : "");                                     // Dust = "yes"
 
     // tool tips
@@ -620,7 +628,11 @@ void CoinControlDialog::updateLabels(WalletModel *model, QDialog* dialog)
     QString toolTip3 = tr("This label turns red, if any recipient receives an amount smaller than %1.").arg(BitcoinUnits::formatWithUnit(nDisplayUnit, ::minRelayTxFee.GetFee(546)));
 
     // how many satoshis the estimated fee can vary per byte we guess wrong
-    double dFeeVary = (double)std::max(CWallet::minTxFee.GetFeePerK(), std::max(payTxFee.GetFeePerK(), mempool.estimateFee(nTxConfirmTarget).GetFeePerK())) / 1000;
+    double dFeeVary;
+    if (payTxFee.GetFeePerK() > 0)
+        dFeeVary = (double)std::max(CWallet::minTxFee.GetFeePerK(), payTxFee.GetFeePerK()) / 1000;
+    else
+        dFeeVary = (double)std::max(CWallet::minTxFee.GetFeePerK(), mempool.estimateFee(nTxConfirmTarget).GetFeePerK()) / 1000;
     QString toolTip4 = tr("Can vary +/- %1 satoshi(s) per input.").arg(dFeeVary);
 
     l3->setToolTip(toolTip4);
@@ -656,6 +668,7 @@ void CoinControlDialog::updateView()
     QFlags<Qt::ItemFlag> flgTristate = Qt::ItemIsSelectable | Qt::ItemIsEnabled | Qt::ItemIsUserCheckable | Qt::ItemIsTristate;
 
     int nDisplayUnit = model->getOptionsModel()->getDisplayUnit();
+    double mempoolEstimatePriority = mempool.estimatePriority(nTxConfirmTarget);
 
     map<QString, vector<COutput> > mapCoins;
     model->listCoins(mapCoins);
@@ -745,7 +758,7 @@ void CoinControlDialog::updateView()
 
             // priority
             double dPriority = ((double)out.tx->vout[out.i].nValue  / (nInputSize + 78)) * (out.nDepth+1); // 78 = 2 * 34 + 10
-            itemOutput->setText(COLUMN_PRIORITY, CoinControlDialog::getPriorityLabel(mempool, dPriority));
+            itemOutput->setText(COLUMN_PRIORITY, CoinControlDialog::getPriorityLabel(dPriority, mempoolEstimatePriority));
             itemOutput->setText(COLUMN_PRIORITY_INT64, strPad(QString::number((int64_t)dPriority), 20, " "));
             dPrioritySum += (double)out.tx->vout[out.i].nValue  * (out.nDepth+1);
             nInputSum    += nInputSize;
@@ -778,7 +791,7 @@ void CoinControlDialog::updateView()
             itemWalletAddress->setText(COLUMN_CHECKBOX, "(" + QString::number(nChildren) + ")");
             itemWalletAddress->setText(COLUMN_AMOUNT, BitcoinUnits::format(nDisplayUnit, nSum));
             itemWalletAddress->setText(COLUMN_AMOUNT_INT64, strPad(QString::number(nSum), 15, " "));
-            itemWalletAddress->setText(COLUMN_PRIORITY, CoinControlDialog::getPriorityLabel(mempool, dPrioritySum));
+            itemWalletAddress->setText(COLUMN_PRIORITY, CoinControlDialog::getPriorityLabel(dPrioritySum, mempoolEstimatePriority));
             itemWalletAddress->setText(COLUMN_PRIORITY_INT64, strPad(QString::number((int64_t)dPrioritySum), 20, " "));
         }
     }
diff --git a/src/qt/coincontroldialog.h b/src/qt/coincontroldialog.h
index cc388d626e..bd4f5d7f1e 100644
--- a/src/qt/coincontroldialog.h
+++ b/src/qt/coincontroldialog.h
@@ -37,7 +37,7 @@ public:
 
     // static because also called from sendcoinsdialog
     static void updateLabels(WalletModel*, QDialog*);
-    static QString getPriorityLabel(const CTxMemPool& pool, double);
+    static QString getPriorityLabel(double dPriority, double mempoolEstimatePriority);
 
     static QList<CAmount> payAmounts;
     static CCoinControl *coinControl;
diff --git a/src/qt/forms/optionsdialog.ui b/src/qt/forms/optionsdialog.ui
index 9d094c1a73..3446cf5c33 100644
--- a/src/qt/forms/optionsdialog.ui
+++ b/src/qt/forms/optionsdialog.ui
@@ -138,65 +138,6 @@
       </attribute>
       <layout class="QVBoxLayout" name="verticalLayout_Wallet">
        <item>
-        <widget class="QLabel" name="transactionFeeInfoLabel">
-         <property name="text">
-          <string>Optional transaction fee per kB that helps make sure your transactions are processed quickly. Most transactions are 1 kB.</string>
-         </property>
-         <property name="textFormat">
-          <enum>Qt::PlainText</enum>
-         </property>
-         <property name="wordWrap">
-          <bool>true</bool>
-         </property>
-        </widget>
-       </item>
-       <item>
-        <layout class="QHBoxLayout" name="horizontalLayout_1_Wallet">
-         <item>
-          <widget class="QLabel" name="transactionFeeLabel">
-           <property name="text">
-            <string>Pay transaction &amp;fee</string>
-           </property>
-           <property name="textFormat">
-            <enum>Qt::PlainText</enum>
-           </property>
-           <property name="buddy">
-            <cstring>transactionFee</cstring>
-           </property>
-          </widget>
-         </item>
-         <item>
-          <widget class="BitcoinAmountField" name="transactionFee"/>
-         </item>
-         <item>
-          <spacer name="horizontalSpacer_1_Wallet">
-           <property name="orientation">
-            <enum>Qt::Horizontal</enum>
-           </property>
-           <property name="sizeHint" stdset="0">
-            <size>
-             <width>40</width>
-             <height>20</height>
-            </size>
-           </property>
-          </spacer>
-         </item>
-        </layout>
-       </item>
-       <item>
-        <spacer name="verticalSpacer_Wallet">
-         <property name="orientation">
-          <enum>Qt::Vertical</enum>
-         </property>
-         <property name="sizeHint" stdset="0">
-          <size>
-           <width>20</width>
-           <height>40</height>
-          </size>
-         </property>
-        </spacer>
-       </item>
-       <item>
         <widget class="QGroupBox" name="groupBox">
          <property name="title">
           <string>Expert</string>
@@ -225,6 +166,19 @@
          </layout>
         </widget>
        </item>
+       <item>
+        <spacer name="verticalSpacer_Wallet">
+         <property name="orientation">
+          <enum>Qt::Vertical</enum>
+         </property>
+         <property name="sizeHint" stdset="0">
+          <size>
+           <width>20</width>
+           <height>40</height>
+          </size>
+         </property>
+        </spacer>
+       </item>
       </layout>
      </widget>
      <widget class="QWidget" name="tabNetwork">
@@ -633,12 +587,6 @@
  </widget>
  <customwidgets>
   <customwidget>
-   <class>BitcoinAmountField</class>
-   <extends>QLineEdit</extends>
-   <header>bitcoinamountfield.h</header>
-   <container>1</container>
-  </customwidget>
-  <customwidget>
    <class>QValidatedLineEdit</class>
    <extends>QLineEdit</extends>
    <header>qvalidatedlineedit.h</header>
diff --git a/src/qt/forms/sendcoinsdialog.ui b/src/qt/forms/sendcoinsdialog.ui
index dce7f4ce4c..0bf04c75eb 100644
--- a/src/qt/forms/sendcoinsdialog.ui
+++ b/src/qt/forms/sendcoinsdialog.ui
@@ -7,13 +7,13 @@
     <x>0</x>
     <y>0</y>
     <width>850</width>
-    <height>400</height>
+    <height>526</height>
    </rect>
   </property>
   <property name="windowTitle">
    <string>Send Coins</string>
   </property>
-  <layout class="QVBoxLayout" name="verticalLayout" stretch="0,1,0">
+  <layout class="QVBoxLayout" name="verticalLayout" stretch="0,1,0,0">
    <property name="bottomMargin">
     <number>8</number>
    </property>
@@ -617,7 +617,7 @@
         <x>0</x>
         <y>0</y>
         <width>830</width>
-        <height>178</height>
+        <height>68</height>
        </rect>
       </property>
       <layout class="QVBoxLayout" name="verticalLayout_2" stretch="0,1">
@@ -658,6 +658,590 @@
     </widget>
    </item>
    <item>
+    <widget class="QFrame" name="frameFee">
+     <property name="sizePolicy">
+      <sizepolicy hsizetype="Expanding" vsizetype="Expanding">
+       <horstretch>0</horstretch>
+       <verstretch>0</verstretch>
+      </sizepolicy>
+     </property>
+     <property name="maximumSize">
+      <size>
+       <width>16777215</width>
+       <height>16777215</height>
+      </size>
+     </property>
+     <property name="frameShape">
+      <enum>QFrame::StyledPanel</enum>
+     </property>
+     <property name="frameShadow">
+      <enum>QFrame::Sunken</enum>
+     </property>
+     <layout class="QVBoxLayout" name="verticalLayoutFee1">
+      <property name="spacing">
+       <number>0</number>
+      </property>
+      <property name="leftMargin">
+       <number>0</number>
+      </property>
+      <property name="topMargin">
+       <number>0</number>
+      </property>
+      <property name="rightMargin">
+       <number>0</number>
+      </property>
+      <property name="bottomMargin">
+       <number>0</number>
+      </property>
+      <item>
+       <layout class="QVBoxLayout" name="verticalLayoutFee2" stretch="0,0,0">
+        <property name="spacing">
+         <number>0</number>
+        </property>
+        <property name="leftMargin">
+         <number>10</number>
+        </property>
+        <property name="topMargin">
+         <number>0</number>
+        </property>
+        <item>
+         <layout class="QHBoxLayout" name="horizontalLayoutFee1">
+          <property name="bottomMargin">
+           <number>0</number>
+          </property>
+          <item>
+           <layout class="QVBoxLayout" name="verticalLayoutFee7">
+            <property name="spacing">
+             <number>0</number>
+            </property>
+            <item>
+             <spacer name="verticalSpacerSmartFee">
+              <property name="orientation">
+               <enum>Qt::Vertical</enum>
+              </property>
+              <property name="sizeType">
+               <enum>QSizePolicy::Fixed</enum>
+              </property>
+              <property name="sizeHint" stdset="0">
+               <size>
+                <width>1</width>
+                <height>4</height>
+               </size>
+              </property>
+             </spacer>
+            </item>
+            <item>
+             <layout class="QHBoxLayout" name="horizontalLayoutSmartFee">
+              <property name="spacing">
+               <number>10</number>
+              </property>
+              <item>
+               <widget class="QLabel" name="labelFeeHeadline">
+                <property name="sizePolicy">
+                 <sizepolicy hsizetype="Preferred" vsizetype="Maximum">
+                  <horstretch>0</horstretch>
+                  <verstretch>0</verstretch>
+                 </sizepolicy>
+                </property>
+                <property name="font">
+                 <font>
+                  <weight>75</weight>
+                  <bold>true</bold>
+                 </font>
+                </property>
+                <property name="styleSheet">
+                 <string notr="true">font-weight:bold;</string>
+                </property>
+                <property name="text">
+                 <string>Transaction Fee:</string>
+                </property>
+               </widget>
+              </item>
+              <item>
+               <widget class="QLabel" name="labelFeeMinimized">
+                <property name="text">
+                 <string/>
+                </property>
+               </widget>
+              </item>
+              <item>
+               <widget class="QPushButton" name="buttonChooseFee">
+                <property name="text">
+                 <string>Choose...</string>
+                </property>
+               </widget>
+              </item>
+              <item>
+               <widget class="QPushButton" name="buttonMinimizeFee">
+                <property name="toolTip">
+                 <string>collapse fee-settings</string>
+                </property>
+                <property name="text">
+                 <string>Minimize</string>
+                </property>
+               </widget>
+              </item>
+             </layout>
+            </item>
+            <item>
+             <spacer name="verticalSpacer_5">
+              <property name="orientation">
+               <enum>Qt::Vertical</enum>
+              </property>
+              <property name="sizeHint" stdset="0">
+               <size>
+                <width>1</width>
+                <height>1</height>
+               </size>
+              </property>
+             </spacer>
+            </item>
+           </layout>
+          </item>
+          <item>
+           <spacer name="horizontalSpacer_4">
+            <property name="orientation">
+             <enum>Qt::Horizontal</enum>
+            </property>
+            <property name="sizeHint" stdset="0">
+             <size>
+              <width>40</width>
+              <height>20</height>
+             </size>
+            </property>
+           </spacer>
+          </item>
+         </layout>
+        </item>
+        <item>
+         <widget class="QFrame" name="frameFeeSelection">
+          <layout class="QVBoxLayout" name="verticalLayoutFee12">
+           <property name="spacing">
+            <number>0</number>
+           </property>
+           <property name="leftMargin">
+            <number>0</number>
+           </property>
+           <property name="topMargin">
+            <number>0</number>
+           </property>
+           <property name="rightMargin">
+            <number>0</number>
+           </property>
+           <property name="bottomMargin">
+            <number>0</number>
+           </property>
+           <item>
+            <layout class="QGridLayout" name="gridLayoutFee">
+             <property name="topMargin">
+              <number>10</number>
+             </property>
+             <property name="bottomMargin">
+              <number>4</number>
+             </property>
+             <property name="horizontalSpacing">
+              <number>10</number>
+             </property>
+             <property name="verticalSpacing">
+              <number>4</number>
+             </property>
+             <item row="1" column="1">
+              <layout class="QVBoxLayout" name="verticalLayoutFee8">
+               <property name="spacing">
+                <number>6</number>
+               </property>
+               <item>
+                <layout class="QHBoxLayout" name="horizontalLayoutFee13">
+                 <item>
+                  <widget class="QRadioButton" name="radioCustomPerKilobyte">
+                   <property name="toolTip">
+                    <string>If the custom fee is set to 1000 satoshis and the transaction is only 250 bytes, then &quot;per kilobyte&quot; only pays 250 satoshis in fee, while &quot;at least&quot; pays 1000 satoshis. For transactions bigger than a kilobyte both pay by kilobyte.</string>
+                   </property>
+                   <property name="text">
+                    <string>per kilobyte</string>
+                   </property>
+                   <property name="checked">
+                    <bool>true</bool>
+                   </property>
+                   <attribute name="buttonGroup">
+                    <string notr="true">groupCustomFee</string>
+                   </attribute>
+                  </widget>
+                 </item>
+                 <item>
+                  <widget class="QRadioButton" name="radioCustomAtLeast">
+                   <property name="toolTip">
+                    <string>If the custom fee is set to 1000 satoshis and the transaction is only 250 bytes, then &quot;per kilobyte&quot; only pays 250 satoshis in fee, while &quot;total at least&quot; pays 1000 satoshis. For transactions bigger than a kilobyte both pay by kilobyte.</string>
+                   </property>
+                   <property name="text">
+                    <string>total at least</string>
+                   </property>
+                   <attribute name="buttonGroup">
+                    <string notr="true">groupCustomFee</string>
+                   </attribute>
+                  </widget>
+                 </item>
+                 <item>
+                  <widget class="BitcoinAmountField" name="customFee"/>
+                 </item>
+                 <item>
+                  <spacer name="horizontalSpacer_6">
+                   <property name="orientation">
+                    <enum>Qt::Horizontal</enum>
+                   </property>
+                   <property name="sizeHint" stdset="0">
+                    <size>
+                     <width>1</width>
+                     <height>1</height>
+                    </size>
+                   </property>
+                  </spacer>
+                 </item>
+                </layout>
+               </item>
+               <item>
+                <layout class="QHBoxLayout" name="horizontalLayoutFee8">
+                 <item>
+                  <widget class="QCheckBox" name="checkBoxMinimumFee">
+                   <property name="toolTip">
+                    <string>Paying only the minimum fee is just fine as long as there is less transaction volume than space in the blocks. But be aware that this can end up in a never confirming transaction once there is more demand for bitcoin transactions than the network can process.</string>
+                   </property>
+                   <property name="text">
+                    <string/>
+                   </property>
+                  </widget>
+                 </item>
+                 <item>
+                  <widget class="QLabel" name="labelMinFeeWarning">
+                   <property name="enabled">
+                    <bool>true</bool>
+                   </property>
+                   <property name="toolTip">
+                    <string>Paying only the minimum fee is just fine as long as there is less transaction volume than space in the blocks. But be aware that this can end up in a never confirming transaction once there is more demand for bitcoin transactions than the network can process.</string>
+                   </property>
+                   <property name="text">
+                    <string>(read the tooltip)</string>
+                   </property>
+                   <property name="margin">
+                    <number>5</number>
+                   </property>
+                  </widget>
+                 </item>
+                 <item>
+                  <spacer name="horizontalSpacer_2">
+                   <property name="orientation">
+                    <enum>Qt::Horizontal</enum>
+                   </property>
+                   <property name="sizeHint" stdset="0">
+                    <size>
+                     <width>1</width>
+                     <height>1</height>
+                    </size>
+                   </property>
+                  </spacer>
+                 </item>
+                </layout>
+               </item>
+              </layout>
+             </item>
+             <item row="0" column="0">
+              <layout class="QVBoxLayout" name="verticalLayoutFee4" stretch="0,1">
+               <item>
+                <widget class="QRadioButton" name="radioSmartFee">
+                 <property name="text">
+                  <string>Recommended:</string>
+                 </property>
+                 <property name="checked">
+                  <bool>true</bool>
+                 </property>
+                 <attribute name="buttonGroup">
+                  <string notr="true">groupFee</string>
+                 </attribute>
+                </widget>
+               </item>
+               <item>
+                <spacer name="verticalSpacer_2">
+                 <property name="orientation">
+                  <enum>Qt::Vertical</enum>
+                 </property>
+                 <property name="sizeHint" stdset="0">
+                  <size>
+                   <width>1</width>
+                   <height>1</height>
+                  </size>
+                 </property>
+                </spacer>
+               </item>
+              </layout>
+             </item>
+             <item row="1" column="0">
+              <layout class="QVBoxLayout" name="verticalLayoutFee9" stretch="0,1">
+               <item>
+                <widget class="QRadioButton" name="radioCustomFee">
+                 <property name="text">
+                  <string>Custom:</string>
+                 </property>
+                 <attribute name="buttonGroup">
+                  <string notr="true">groupFee</string>
+                 </attribute>
+                </widget>
+               </item>
+               <item>
+                <spacer name="verticalSpacer_6">
+                 <property name="orientation">
+                  <enum>Qt::Vertical</enum>
+                 </property>
+                 <property name="sizeHint" stdset="0">
+                  <size>
+                   <width>1</width>
+                   <height>1</height>
+                  </size>
+                 </property>
+                </spacer>
+               </item>
+              </layout>
+             </item>
+             <item row="0" column="1">
+              <layout class="QVBoxLayout" name="verticalLayoutFee3" stretch="0,0,1">
+               <property name="spacing">
+                <number>6</number>
+               </property>
+               <property name="topMargin">
+                <number>2</number>
+               </property>
+               <item>
+                <layout class="QHBoxLayout" name="horizontalLayoutFee12">
+                 <item>
+                  <widget class="QLabel" name="labelSmartFee">
+                   <property name="text">
+                    <string/>
+                   </property>
+                   <property name="margin">
+                    <number>2</number>
+                   </property>
+                  </widget>
+                 </item>
+                 <item>
+                  <widget class="QLabel" name="labelFeeEstimation">
+                   <property name="text">
+                    <string/>
+                   </property>
+                  </widget>
+                 </item>
+                 <item>
+                  <widget class="QLabel" name="labelSmartFee2">
+                   <property name="text">
+                    <string>(Smart fee not initialized yet. This usually takes a few blocks...)</string>
+                   </property>
+                   <property name="margin">
+                    <number>2</number>
+                   </property>
+                  </widget>
+                 </item>
+                 <item>
+                  <spacer name="horizontalSpacer_5">
+                   <property name="orientation">
+                    <enum>Qt::Horizontal</enum>
+                   </property>
+                   <property name="sizeHint" stdset="0">
+                    <size>
+                     <width>1</width>
+                     <height>1</height>
+                    </size>
+                   </property>
+                  </spacer>
+                 </item>
+                </layout>
+               </item>
+               <item>
+                <layout class="QHBoxLayout" name="horizontalLayoutFee9">
+                 <item>
+                  <layout class="QVBoxLayout" name="verticalLayoutFee6">
+                   <item>
+                    <widget class="QLabel" name="labelSmartFee3">
+                     <property name="text">
+                      <string>Confirmation time:</string>
+                     </property>
+                     <property name="margin">
+                      <number>2</number>
+                     </property>
+                    </widget>
+                   </item>
+                   <item>
+                    <spacer name="verticalSpacer_3">
+                     <property name="orientation">
+                      <enum>Qt::Vertical</enum>
+                     </property>
+                     <property name="sizeHint" stdset="0">
+                      <size>
+                       <width>1</width>
+                       <height>1</height>
+                      </size>
+                     </property>
+                    </spacer>
+                   </item>
+                  </layout>
+                 </item>
+                 <item>
+                  <layout class="QVBoxLayout" name="verticalLayoutFee5">
+                   <property name="rightMargin">
+                    <number>30</number>
+                   </property>
+                   <item>
+                    <widget class="QSlider" name="sliderSmartFee">
+                     <property name="minimum">
+                      <number>0</number>
+                     </property>
+                     <property name="maximum">
+                      <number>24</number>
+                     </property>
+                     <property name="pageStep">
+                      <number>1</number>
+                     </property>
+                     <property name="value">
+                      <number>0</number>
+                     </property>
+                     <property name="orientation">
+                      <enum>Qt::Horizontal</enum>
+                     </property>
+                     <property name="invertedAppearance">
+                      <bool>false</bool>
+                     </property>
+                     <property name="invertedControls">
+                      <bool>false</bool>
+                     </property>
+                     <property name="tickPosition">
+                      <enum>QSlider::NoTicks</enum>
+                     </property>
+                    </widget>
+                   </item>
+                   <item>
+                    <layout class="QHBoxLayout" name="horizontalLayoutFee10">
+                     <item>
+                      <widget class="QLabel" name="labelSmartFeeNormal">
+                       <property name="text">
+                        <string>normal</string>
+                       </property>
+                      </widget>
+                     </item>
+                     <item>
+                      <spacer name="horizontalSpacer_3">
+                       <property name="orientation">
+                        <enum>Qt::Horizontal</enum>
+                       </property>
+                       <property name="sizeHint" stdset="0">
+                        <size>
+                         <width>40</width>
+                         <height>20</height>
+                        </size>
+                       </property>
+                      </spacer>
+                     </item>
+                     <item>
+                      <widget class="QLabel" name="labelSmartFeeFast">
+                       <property name="text">
+                        <string>fast</string>
+                       </property>
+                      </widget>
+                     </item>
+                    </layout>
+                   </item>
+                  </layout>
+                 </item>
+                </layout>
+               </item>
+               <item>
+                <spacer name="verticalSpacer_4">
+                 <property name="orientation">
+                  <enum>Qt::Vertical</enum>
+                 </property>
+                 <property name="sizeHint" stdset="0">
+                  <size>
+                   <width>1</width>
+                   <height>1</height>
+                  </size>
+                 </property>
+                </spacer>
+               </item>
+              </layout>
+             </item>
+            </layout>
+           </item>
+           <item>
+            <layout class="QHBoxLayout" name="horizontalLayoutFee5" stretch="0,0,0">
+             <property name="spacing">
+              <number>8</number>
+             </property>
+             <property name="bottomMargin">
+              <number>4</number>
+             </property>
+             <item>
+              <widget class="QCheckBox" name="checkBoxFreeTx">
+               <property name="text">
+                <string>Send as zero-fee transaction if possible</string>
+               </property>
+              </widget>
+             </item>
+             <item>
+              <widget class="QLabel" name="labelFreeTx">
+               <property name="text">
+                <string>(confirmation may take longer)</string>
+               </property>
+               <property name="margin">
+                <number>5</number>
+               </property>
+              </widget>
+             </item>
+             <item>
+              <spacer name="horizontalSpacerFee5">
+               <property name="orientation">
+                <enum>Qt::Horizontal</enum>
+               </property>
+               <property name="sizeHint" stdset="0">
+                <size>
+                 <width>1</width>
+                 <height>1</height>
+                </size>
+               </property>
+              </spacer>
+             </item>
+            </layout>
+           </item>
+           <item>
+            <spacer name="verticalSpacerFee2">
+             <property name="orientation">
+              <enum>Qt::Vertical</enum>
+             </property>
+             <property name="sizeHint" stdset="0">
+              <size>
+               <width>1</width>
+               <height>1</height>
+              </size>
+             </property>
+            </spacer>
+           </item>
+          </layout>
+         </widget>
+        </item>
+        <item>
+         <spacer name="verticalSpacerFee">
+          <property name="orientation">
+           <enum>Qt::Vertical</enum>
+          </property>
+          <property name="sizeHint" stdset="0">
+           <size>
+            <width>800</width>
+            <height>1</height>
+           </size>
+          </property>
+         </spacer>
+        </item>
+       </layout>
+      </item>
+     </layout>
+    </widget>
+   </item>
+   <item>
     <layout class="QHBoxLayout" name="horizontalLayout">
      <item>
       <widget class="QPushButton" name="sendButton">
@@ -787,9 +1371,19 @@
    <extends>QLineEdit</extends>
    <header>qvalidatedlineedit.h</header>
   </customwidget>
+  <customwidget>
+   <class>BitcoinAmountField</class>
+   <extends>QLineEdit</extends>
+   <header>bitcoinamountfield.h</header>
+   <container>1</container>
+  </customwidget>
  </customwidgets>
  <resources>
   <include location="../bitcoin.qrc"/>
  </resources>
  <connections/>
+ <buttongroups>
+  <buttongroup name="groupFee"/>
+  <buttongroup name="groupCustomFee"/>
+ </buttongroups>
 </ui>
diff --git a/src/qt/optionsdialog.cpp b/src/qt/optionsdialog.cpp
index f5a0759c92..069080219e 100644
--- a/src/qt/optionsdialog.cpp
+++ b/src/qt/optionsdialog.cpp
@@ -105,9 +105,6 @@ OptionsDialog::OptionsDialog(QWidget *parent, bool enableWallet) :
 #endif
 
     ui->unit->setModel(new BitcoinUnits(this));
-#ifdef ENABLE_WALLET
-    ui->transactionFee->setSingleStep(CWallet::minTxFee.GetFeePerK());
-#endif
 
     /* Widget-to-option mapper */
     mapper = new QDataWidgetMapper(this);
@@ -139,16 +136,11 @@ void OptionsDialog::setModel(OptionsModel *model)
             strLabel = tr("none");
         ui->overriddenByCommandLineLabel->setText(strLabel);
 
-        connect(model, SIGNAL(displayUnitChanged(int)), this, SLOT(updateDisplayUnit()));
-
         mapper->setModel(model);
         setMapper();
         mapper->toFirst();
     }
 
-    /* update the display unit, to not use the default ("BTC") */
-    updateDisplayUnit();
-
     /* warn when one of the following settings changes by user action (placed here so init via mapper doesn't trigger them) */
 
     /* Main */
@@ -172,7 +164,6 @@ void OptionsDialog::setMapper()
     mapper->addMapping(ui->databaseCache, OptionsModel::DatabaseCache);
 
     /* Wallet */
-    mapper->addMapping(ui->transactionFee, OptionsModel::Fee);
     mapper->addMapping(ui->spendZeroConfChange, OptionsModel::SpendZeroConfChange);
     mapper->addMapping(ui->coinControlFeatures, OptionsModel::CoinControlFeatures);
 
@@ -264,15 +255,6 @@ void OptionsDialog::clearStatusLabel()
     ui->statusLabel->clear();
 }
 
-void OptionsDialog::updateDisplayUnit()
-{
-    if(model)
-    {
-        /* Update transactionFee with the current unit */
-        ui->transactionFee->setDisplayUnit(model->getDisplayUnit());
-    }
-}
-
 void OptionsDialog::doProxyIpChecks(QValidatedLineEdit *pUiProxyIp, int nProxyPort)
 {
     Q_UNUSED(nProxyPort);
diff --git a/src/qt/optionsdialog.h b/src/qt/optionsdialog.h
index 794a39590c..511719f53c 100644
--- a/src/qt/optionsdialog.h
+++ b/src/qt/optionsdialog.h
@@ -46,7 +46,6 @@ private slots:
 
     void showRestartWarning(bool fPersistent = false);
     void clearStatusLabel();
-    void updateDisplayUnit();
     void doProxyIpChecks(QValidatedLineEdit *pUiProxyIp, int nProxyPort);
 
 signals:
diff --git a/src/qt/optionsmodel.cpp b/src/qt/optionsmodel.cpp
index c941ebd4ca..7054509fe6 100644
--- a/src/qt/optionsmodel.cpp
+++ b/src/qt/optionsmodel.cpp
@@ -90,12 +90,6 @@ void OptionsModel::Init()
 
     // Wallet
 #ifdef ENABLE_WALLET
-    if (!settings.contains("nTransactionFee"))
-        settings.setValue("nTransactionFee", (qint64)DEFAULT_TRANSACTION_FEE);
-    payTxFee = CFeeRate(settings.value("nTransactionFee").toLongLong()); // if -paytxfee is set, this will be overridden later in init.cpp
-    if (mapArgs.count("-paytxfee"))
-        addOverriddenOption("-paytxfee");
-
     if (!settings.contains("bSpendZeroConfChange"))
         settings.setValue("bSpendZeroConfChange", true);
     if (!SoftSetBoolArg("-spendzeroconfchange", settings.value("bSpendZeroConfChange").toBool()))
@@ -185,16 +179,6 @@ QVariant OptionsModel::data(const QModelIndex & index, int role) const
         }
 
 #ifdef ENABLE_WALLET
-        case Fee: {
-            // Attention: Init() is called before payTxFee is set in AppInit2()!
-            // To ensure we can change the fee on-the-fly update our QSetting when
-            // opening OptionsDialog, which queries Fee via the mapper.
-            if (!(payTxFee == CFeeRate(settings.value("nTransactionFee").toLongLong(), 1000)))
-                settings.setValue("nTransactionFee", (qint64)payTxFee.GetFeePerK());
-            // Todo: Consider to revert back to use just payTxFee here, if we don't want
-            // -paytxfee to update our QSettings!
-            return settings.value("nTransactionFee");
-        }
         case SpendZeroConfChange:
             return settings.value("bSpendZeroConfChange");
 #endif
@@ -276,14 +260,6 @@ bool OptionsModel::setData(const QModelIndex & index, const QVariant & value, in
         }
         break;
 #ifdef ENABLE_WALLET
-        case Fee: { // core option - can be changed on-the-fly
-            // Todo: Add is valid check  and warn via message, if not
-            CAmount nTransactionFee(value.toLongLong());
-            payTxFee = CFeeRate(nTransactionFee, 1000);
-            settings.setValue("nTransactionFee", qint64(nTransactionFee));
-            emit transactionFeeChanged(nTransactionFee);
-            break;
-        }
         case SpendZeroConfChange:
             if (settings.value("bSpendZeroConfChange") != value) {
                 settings.setValue("bSpendZeroConfChange", value);
diff --git a/src/qt/optionsmodel.h b/src/qt/optionsmodel.h
index e2dc067edb..84fd49a7b8 100644
--- a/src/qt/optionsmodel.h
+++ b/src/qt/optionsmodel.h
@@ -34,7 +34,6 @@ public:
         ProxyUse,               // bool
         ProxyIP,                // QString
         ProxyPort,              // int
-        Fee,                    // qint64
         DisplayUnit,            // BitcoinUnits::Unit
         ThirdPartyTxUrls,       // QString
         Language,               // QString
@@ -84,7 +83,6 @@ private:
 
 signals:
     void displayUnitChanged(int unit);
-    void transactionFeeChanged(const CAmount&);
     void coinControlFeaturesChanged(bool);
 };
 
diff --git a/src/qt/sendcoinsdialog.cpp b/src/qt/sendcoinsdialog.cpp
index ce94131cce..ff39829b95 100644
--- a/src/qt/sendcoinsdialog.cpp
+++ b/src/qt/sendcoinsdialog.cpp
@@ -7,10 +7,12 @@
 
 #include "addresstablemodel.h"
 #include "bitcoinunits.h"
+#include "clientmodel.h"
 #include "coincontroldialog.h"
 #include "guiutil.h"
 #include "optionsmodel.h"
 #include "sendcoinsentry.h"
+#include "wallet.h"
 #include "walletmodel.h"
 
 #include "base58.h"
@@ -19,6 +21,7 @@
 
 #include <QMessageBox>
 #include <QScrollBar>
+#include <QSettings>
 #include <QTextDocument>
 
 SendCoinsDialog::SendCoinsDialog(QWidget *parent) :
@@ -72,9 +75,46 @@ SendCoinsDialog::SendCoinsDialog(QWidget *parent) :
     ui->labelCoinControlLowOutput->addAction(clipboardLowOutputAction);
     ui->labelCoinControlChange->addAction(clipboardChangeAction);
 
+    // init transaction fee section
+    QSettings settings;
+    if (!settings.contains("fFeeSectionMinimized"))
+        settings.setValue("fFeeSectionMinimized", true);
+    if (!settings.contains("nFeeRadio") && settings.contains("nTransactionFee") && settings.value("nTransactionFee").toLongLong() > 0) // compatibility
+        settings.setValue("nFeeRadio", 1); // custom
+    if (!settings.contains("nFeeRadio"))
+        settings.setValue("nFeeRadio", 0); // recommended
+    if (!settings.contains("nCustomFeeRadio") && settings.contains("nTransactionFee") && settings.value("nTransactionFee").toLongLong() > 0) // compatibility
+        settings.setValue("nCustomFeeRadio", 1); // total at least
+    if (!settings.contains("nCustomFeeRadio"))
+        settings.setValue("nCustomFeeRadio", 0); // per kilobyte
+    if (!settings.contains("nSmartFeeSliderPosition"))
+        settings.setValue("nSmartFeeSliderPosition", 0);
+    if (!settings.contains("nTransactionFee"))
+        settings.setValue("nTransactionFee", (qint64)DEFAULT_TRANSACTION_FEE);
+    if (!settings.contains("fPayOnlyMinFee"))
+        settings.setValue("fPayOnlyMinFee", false);
+    if (!settings.contains("fSendFreeTransactions"))
+        settings.setValue("fSendFreeTransactions", false);
+    ui->groupFee->setId(ui->radioSmartFee, 0);
+    ui->groupFee->setId(ui->radioCustomFee, 1);
+    ui->groupFee->button((int)std::max(0, std::min(1, settings.value("nFeeRadio").toInt())))->setChecked(true);
+    ui->groupCustomFee->setId(ui->radioCustomPerKilobyte, 0);
+    ui->groupCustomFee->setId(ui->radioCustomAtLeast, 1);
+    ui->groupCustomFee->button((int)std::max(0, std::min(1, settings.value("nCustomFeeRadio").toInt())))->setChecked(true);
+    ui->sliderSmartFee->setValue(settings.value("nSmartFeeSliderPosition").toInt());
+    ui->customFee->setValue(settings.value("nTransactionFee").toLongLong());
+    ui->checkBoxMinimumFee->setChecked(settings.value("fPayOnlyMinFee").toBool());
+    ui->checkBoxFreeTx->setChecked(settings.value("fSendFreeTransactions").toBool());
+    minimizeFeeSection(settings.value("fFeeSectionMinimized").toBool());
+
     fNewRecipientAllowed = true;
 }
 
+void SendCoinsDialog::setClientModel(ClientModel *clientModel)
+{
+    this->clientModel = clientModel;
+}
+
 void SendCoinsDialog::setModel(WalletModel *model)
 {
     this->model = model;
@@ -94,18 +134,51 @@ void SendCoinsDialog::setModel(WalletModel *model)
                    model->getWatchBalance(), model->getWatchUnconfirmedBalance(), model->getWatchImmatureBalance());
         connect(model, SIGNAL(balanceChanged(CAmount,CAmount,CAmount,CAmount,CAmount,CAmount)), this, SLOT(setBalance(CAmount,CAmount,CAmount,CAmount,CAmount,CAmount)));
         connect(model->getOptionsModel(), SIGNAL(displayUnitChanged(int)), this, SLOT(updateDisplayUnit()));
+        updateDisplayUnit();
 
         // Coin Control
         connect(model->getOptionsModel(), SIGNAL(displayUnitChanged(int)), this, SLOT(coinControlUpdateLabels()));
         connect(model->getOptionsModel(), SIGNAL(coinControlFeaturesChanged(bool)), this, SLOT(coinControlFeatureChanged(bool)));
-        connect(model->getOptionsModel(), SIGNAL(transactionFeeChanged(CAmount)), this, SLOT(coinControlUpdateLabels()));
         ui->frameCoinControl->setVisible(model->getOptionsModel()->getCoinControlFeatures());
         coinControlUpdateLabels();
+
+        // fee section
+        connect(clientModel, SIGNAL(numBlocksChanged(int)), this, SLOT(updateSmartFeeLabel()));
+        connect(ui->sliderSmartFee, SIGNAL(valueChanged(int)), this, SLOT(updateSmartFeeLabel()));
+        connect(ui->sliderSmartFee, SIGNAL(valueChanged(int)), this, SLOT(updateGlobalFeeVariables()));
+        connect(ui->sliderSmartFee, SIGNAL(valueChanged(int)), this, SLOT(coinControlUpdateLabels()));
+        connect(ui->groupFee, SIGNAL(buttonClicked(int)), this, SLOT(updateFeeSectionControls()));
+        connect(ui->groupFee, SIGNAL(buttonClicked(int)), this, SLOT(updateGlobalFeeVariables()));
+        connect(ui->groupFee, SIGNAL(buttonClicked(int)), this, SLOT(coinControlUpdateLabels()));
+        connect(ui->groupCustomFee, SIGNAL(buttonClicked(int)), this, SLOT(updateGlobalFeeVariables()));
+        connect(ui->groupCustomFee, SIGNAL(buttonClicked(int)), this, SLOT(coinControlUpdateLabels()));
+        connect(ui->customFee, SIGNAL(valueChanged()), this, SLOT(updateGlobalFeeVariables()));
+        connect(ui->customFee, SIGNAL(valueChanged()), this, SLOT(coinControlUpdateLabels()));
+        connect(ui->checkBoxMinimumFee, SIGNAL(stateChanged(int)), this, SLOT(setMinimumFee()));
+        connect(ui->checkBoxMinimumFee, SIGNAL(stateChanged(int)), this, SLOT(updateFeeSectionControls()));
+        connect(ui->checkBoxMinimumFee, SIGNAL(stateChanged(int)), this, SLOT(updateGlobalFeeVariables()));
+        connect(ui->checkBoxMinimumFee, SIGNAL(stateChanged(int)), this, SLOT(coinControlUpdateLabels()));
+        connect(ui->checkBoxFreeTx, SIGNAL(stateChanged(int)), this, SLOT(updateGlobalFeeVariables()));
+        connect(ui->checkBoxFreeTx, SIGNAL(stateChanged(int)), this, SLOT(coinControlUpdateLabels()));
+        ui->customFee->setSingleStep(CWallet::minTxFee.GetFeePerK());
+        updateFeeSectionControls();
+        updateMinFeeLabel();
+        updateSmartFeeLabel();
+        updateGlobalFeeVariables();
     }
 }
 
 SendCoinsDialog::~SendCoinsDialog()
 {
+    QSettings settings;
+    settings.setValue("fFeeSectionMinimized", fFeeMinimized);
+    settings.setValue("nFeeRadio", ui->groupFee->checkedId());
+    settings.setValue("nCustomFeeRadio", ui->groupCustomFee->checkedId());
+    settings.setValue("nSmartFeeSliderPosition", ui->sliderSmartFee->value());
+    settings.setValue("nTransactionFee", (qint64)ui->customFee->value());
+    settings.setValue("fPayOnlyMinFee", ui->checkBoxMinimumFee->isChecked());
+    settings.setValue("fSendFreeTransactions", ui->checkBoxFreeTx->isChecked());
+
     delete ui;
 }
 
@@ -214,6 +287,9 @@ void SendCoinsDialog::on_sendButton_clicked()
         questionString.append(BitcoinUnits::formatHtmlWithUnit(model->getOptionsModel()->getDisplayUnit(), txFee));
         questionString.append("</span> ");
         questionString.append(tr("added as transaction fee"));
+
+        // append transaction size
+        questionString.append(" (" + QString::number((double)currentTransaction.getTransactionSize() / 1000) + " kB)");
     }
 
     // add total amount in all subdivision units
@@ -402,6 +478,9 @@ void SendCoinsDialog::setBalance(const CAmount& balance, const CAmount& unconfir
 void SendCoinsDialog::updateDisplayUnit()
 {
     setBalance(model->getBalance(), 0, 0, 0, 0, 0);
+    ui->customFee->setDisplayUnit(model->getOptionsModel()->getDisplayUnit());
+    updateMinFeeLabel();
+    updateSmartFeeLabel();
 }
 
 void SendCoinsDialog::processSendCoinsReturn(const WalletModel::SendCoinsReturn &sendCoinsReturn, const QString &msgArg)
@@ -438,6 +517,9 @@ void SendCoinsDialog::processSendCoinsReturn(const WalletModel::SendCoinsReturn
         msgParams.first = tr("The transaction was rejected! This might happen if some of the coins in your wallet were already spent, such as if you used a copy of wallet.dat and coins were spent in the copy but not marked as spent here.");
         msgParams.second = CClientUIInterface::MSG_ERROR;
         break;
+    case WalletModel::InsaneFee:
+        msgParams.first = tr("A fee higher than %1 is considered an insanely high fee.").arg(BitcoinUnits::formatWithUnit(model->getOptionsModel()->getDisplayUnit(), 10000000));
+        break;
     // included to prevent a compiler warning.
     case WalletModel::OK:
     default:
@@ -447,6 +529,110 @@ void SendCoinsDialog::processSendCoinsReturn(const WalletModel::SendCoinsReturn
     emit message(tr("Send Coins"), msgParams.first, msgParams.second);
 }
 
+void SendCoinsDialog::minimizeFeeSection(bool fMinimize)
+{
+    ui->labelFeeMinimized->setVisible(fMinimize);
+    ui->buttonChooseFee  ->setVisible(fMinimize);
+    ui->buttonMinimizeFee->setVisible(!fMinimize);
+    ui->frameFeeSelection->setVisible(!fMinimize);
+    ui->horizontalLayoutSmartFee->setContentsMargins(0, (fMinimize ? 0 : 6), 0, 0);
+    fFeeMinimized = fMinimize;
+}
+
+void SendCoinsDialog::on_buttonChooseFee_clicked()
+{
+    minimizeFeeSection(false);
+}
+
+void SendCoinsDialog::on_buttonMinimizeFee_clicked()
+{
+    updateFeeMinimizedLabel();
+    minimizeFeeSection(true);
+}
+
+void SendCoinsDialog::setMinimumFee()
+{
+    ui->radioCustomPerKilobyte->setChecked(true);
+    ui->customFee->setValue(CWallet::minTxFee.GetFeePerK());
+}
+
+void SendCoinsDialog::updateFeeSectionControls()
+{
+    ui->sliderSmartFee          ->setEnabled(ui->radioSmartFee->isChecked());
+    ui->labelSmartFee           ->setEnabled(ui->radioSmartFee->isChecked());
+    ui->labelSmartFee2          ->setEnabled(ui->radioSmartFee->isChecked());
+    ui->labelSmartFee3          ->setEnabled(ui->radioSmartFee->isChecked());
+    ui->labelFeeEstimation      ->setEnabled(ui->radioSmartFee->isChecked());
+    ui->labelSmartFeeNormal     ->setEnabled(ui->radioSmartFee->isChecked());
+    ui->labelSmartFeeFast       ->setEnabled(ui->radioSmartFee->isChecked());
+    ui->checkBoxMinimumFee      ->setEnabled(ui->radioCustomFee->isChecked());
+    ui->labelMinFeeWarning      ->setEnabled(ui->radioCustomFee->isChecked());
+    ui->radioCustomPerKilobyte  ->setEnabled(ui->radioCustomFee->isChecked() && !ui->checkBoxMinimumFee->isChecked());
+    ui->radioCustomAtLeast      ->setEnabled(ui->radioCustomFee->isChecked() && !ui->checkBoxMinimumFee->isChecked());
+    ui->customFee               ->setEnabled(ui->radioCustomFee->isChecked() && !ui->checkBoxMinimumFee->isChecked());
+}
+
+void SendCoinsDialog::updateGlobalFeeVariables()
+{
+    if (ui->radioSmartFee->isChecked())
+    {
+        nTxConfirmTarget = (int)25 - (int)std::max(0, std::min(24, ui->sliderSmartFee->value()));
+        payTxFee = CFeeRate(0);
+    }
+    else
+    {
+        nTxConfirmTarget = 25;
+        payTxFee = CFeeRate(ui->customFee->value());
+        fPayAtLeastCustomFee = ui->radioCustomAtLeast->isChecked();
+    }
+
+    fSendFreeTransactions = ui->checkBoxFreeTx->isChecked();
+}
+
+void SendCoinsDialog::updateFeeMinimizedLabel()
+{
+    if(!model || !model->getOptionsModel())
+        return;
+
+    if (ui->radioSmartFee->isChecked())
+        ui->labelFeeMinimized->setText(ui->labelSmartFee->text());
+    else {
+        ui->labelFeeMinimized->setText(BitcoinUnits::formatWithUnit(model->getOptionsModel()->getDisplayUnit(), ui->customFee->value()) +
+            ((ui->radioCustomPerKilobyte->isChecked()) ? "/kB" : ""));
+    }
+}
+
+void SendCoinsDialog::updateMinFeeLabel()
+{
+    if (model && model->getOptionsModel())
+        ui->checkBoxMinimumFee->setText(tr("Pay only the minimum fee of %1").arg(
+            BitcoinUnits::formatWithUnit(model->getOptionsModel()->getDisplayUnit(), CWallet::minTxFee.GetFeePerK()) + "/kB")
+        );
+}
+
+void SendCoinsDialog::updateSmartFeeLabel()
+{
+    if(!model || !model->getOptionsModel())
+        return;
+
+    int nBlocksToConfirm = (int)25 - (int)std::max(0, std::min(24, ui->sliderSmartFee->value()));
+    CFeeRate feeRate = mempool.estimateFee(nBlocksToConfirm);
+    if (feeRate <= CFeeRate(0)) // not enough data => minfee
+    {
+        ui->labelSmartFee->setText(BitcoinUnits::formatWithUnit(model->getOptionsModel()->getDisplayUnit(), CWallet::minTxFee.GetFeePerK()) + "/kB");
+        ui->labelSmartFee2->show(); // (Smart fee not initialized yet. This usually takes a few blocks...)
+        ui->labelFeeEstimation->setText("");
+    }
+    else
+    {
+        ui->labelSmartFee->setText(BitcoinUnits::formatWithUnit(model->getOptionsModel()->getDisplayUnit(), feeRate.GetFeePerK()) + "/kB");
+        ui->labelSmartFee2->hide();
+        ui->labelFeeEstimation->setText(tr("Estimated to begin confirmation within %1 block(s).").arg(nBlocksToConfirm));
+    }
+
+    updateFeeMinimizedLabel();
+}
+
 // Coin Control: copy label "Quantity" to clipboard
 void SendCoinsDialog::coinControlClipboardQuantity()
 {
@@ -462,19 +648,19 @@ void SendCoinsDialog::coinControlClipboardAmount()
 // Coin Control: copy label "Fee" to clipboard
 void SendCoinsDialog::coinControlClipboardFee()
 {
-    GUIUtil::setClipboard(ui->labelCoinControlFee->text().left(ui->labelCoinControlFee->text().indexOf(" ")));
+    GUIUtil::setClipboard(ui->labelCoinControlFee->text().left(ui->labelCoinControlFee->text().indexOf(" ")).replace("~", ""));
 }
 
 // Coin Control: copy label "After fee" to clipboard
 void SendCoinsDialog::coinControlClipboardAfterFee()
 {
-    GUIUtil::setClipboard(ui->labelCoinControlAfterFee->text().left(ui->labelCoinControlAfterFee->text().indexOf(" ")));
+    GUIUtil::setClipboard(ui->labelCoinControlAfterFee->text().left(ui->labelCoinControlAfterFee->text().indexOf(" ")).replace("~", ""));
 }
 
 // Coin Control: copy label "Bytes" to clipboard
 void SendCoinsDialog::coinControlClipboardBytes()
 {
-    GUIUtil::setClipboard(ui->labelCoinControlBytes->text());
+    GUIUtil::setClipboard(ui->labelCoinControlBytes->text().replace("~", ""));
 }
 
 // Coin Control: copy label "Priority" to clipboard
@@ -492,7 +678,7 @@ void SendCoinsDialog::coinControlClipboardLowOutput()
 // Coin Control: copy label "Change" to clipboard
 void SendCoinsDialog::coinControlClipboardChange()
 {
-    GUIUtil::setClipboard(ui->labelCoinControlChange->text().left(ui->labelCoinControlChange->text().indexOf(" ")));
+    GUIUtil::setClipboard(ui->labelCoinControlChange->text().left(ui->labelCoinControlChange->text().indexOf(" ")).replace("~", ""));
 }
 
 // Coin Control: settings menu - coin control enabled/disabled by user
diff --git a/src/qt/sendcoinsdialog.h b/src/qt/sendcoinsdialog.h
index eec661cbd0..15d39782a1 100644
--- a/src/qt/sendcoinsdialog.h
+++ b/src/qt/sendcoinsdialog.h
@@ -10,6 +10,7 @@
 #include <QDialog>
 #include <QString>
 
+class ClientModel;
 class OptionsModel;
 class SendCoinsEntry;
 class SendCoinsRecipient;
@@ -31,6 +32,7 @@ public:
     explicit SendCoinsDialog(QWidget *parent = 0);
     ~SendCoinsDialog();
 
+    void setClientModel(ClientModel *clientModel);
     void setModel(WalletModel *model);
 
     /** Set up the tab chain manually, as Qt messes up the tab chain by default in some cases (issue https://bugreports.qt-project.org/browse/QTBUG-10907).
@@ -52,16 +54,22 @@ public slots:
 
 private:
     Ui::SendCoinsDialog *ui;
+    ClientModel *clientModel;
     WalletModel *model;
     bool fNewRecipientAllowed;
+    bool fFeeMinimized;
 
     // Process WalletModel::SendCoinsReturn and generate a pair consisting
     // of a message and message flags for use in emit message().
     // Additional parameter msgArg can be used via .arg(msgArg).
     void processSendCoinsReturn(const WalletModel::SendCoinsReturn &sendCoinsReturn, const QString &msgArg = QString());
+    void minimizeFeeSection(bool fMinimize);
+    void updateFeeMinimizedLabel();
 
 private slots:
     void on_sendButton_clicked();
+    void on_buttonChooseFee_clicked();
+    void on_buttonMinimizeFee_clicked();
     void removeEntry(SendCoinsEntry* entry);
     void updateDisplayUnit();
     void coinControlFeatureChanged(bool);
@@ -77,6 +85,11 @@ private slots:
     void coinControlClipboardPriority();
     void coinControlClipboardLowOutput();
     void coinControlClipboardChange();
+    void setMinimumFee();
+    void updateFeeSectionControls();
+    void updateMinFeeLabel();
+    void updateSmartFeeLabel();
+    void updateGlobalFeeVariables();
 
 signals:
     // Fired when a message should be reported to the user
diff --git a/src/qt/walletmodel.cpp b/src/qt/walletmodel.cpp
index f7b1552f3e..b20465794d 100644
--- a/src/qt/walletmodel.cpp
+++ b/src/qt/walletmodel.cpp
@@ -277,6 +277,10 @@ WalletModel::SendCoinsReturn WalletModel::prepareTransaction(WalletModelTransact
                          CClientUIInterface::MSG_ERROR);
             return TransactionCreationFailed;
         }
+
+        // reject insane fee > 0.1 bitcoin
+        if (nFeeRequired > 10000000)
+            return InsaneFee;
     }
 
     return SendCoinsReturn(OK);
diff --git a/src/qt/walletmodel.h b/src/qt/walletmodel.h
index 0c6077963d..d7e391f8d1 100644
--- a/src/qt/walletmodel.h
+++ b/src/qt/walletmodel.h
@@ -110,7 +110,8 @@ public:
         AmountWithFeeExceedsBalance,
         DuplicateAddress,
         TransactionCreationFailed, // Error returned when wallet is still locked
-        TransactionCommitFailed
+        TransactionCommitFailed,
+        InsaneFee
     };
 
     enum EncryptionStatus
diff --git a/src/qt/walletmodeltransaction.cpp b/src/qt/walletmodeltransaction.cpp
index ddd2d09bb5..e9e20c7d51 100644
--- a/src/qt/walletmodeltransaction.cpp
+++ b/src/qt/walletmodeltransaction.cpp
@@ -31,6 +31,11 @@ CWalletTx *WalletModelTransaction::getTransaction()
     return walletTransaction;
 }
 
+unsigned int WalletModelTransaction::getTransactionSize()
+{
+    return (!walletTransaction ? 0 : (::GetSerializeSize(*(CTransaction*)walletTransaction, SER_NETWORK, PROTOCOL_VERSION)));
+}
+
 CAmount WalletModelTransaction::getTransactionFee()
 {
     return fee;
diff --git a/src/qt/walletmodeltransaction.h b/src/qt/walletmodeltransaction.h
index a880384ed6..4272529abe 100644
--- a/src/qt/walletmodeltransaction.h
+++ b/src/qt/walletmodeltransaction.h
@@ -25,6 +25,7 @@ public:
     QList<SendCoinsRecipient> getRecipients();
 
     CWalletTx *getTransaction();
+    unsigned int getTransactionSize();
 
     void setTransactionFee(const CAmount& newFee);
     CAmount getTransactionFee();
diff --git a/src/qt/walletview.cpp b/src/qt/walletview.cpp
index 3b8fdd7e5f..9bab180108 100644
--- a/src/qt/walletview.cpp
+++ b/src/qt/walletview.cpp
@@ -101,6 +101,7 @@ void WalletView::setClientModel(ClientModel *clientModel)
     this->clientModel = clientModel;
 
     overviewPage->setClientModel(clientModel);
+    sendCoinsPage->setClientModel(clientModel);
 }
 
 void WalletView::setWalletModel(WalletModel *walletModel)
diff --git a/src/txmempool.h b/src/txmempool.h
index 0d3c8bba6a..e68b218154 100644
--- a/src/txmempool.h
+++ b/src/txmempool.h
@@ -15,11 +15,16 @@
 
 class CAutoFile;
 
+inline double AllowFreeThreshold()
+{
+    return COIN * 144 / 250;
+}
+
 inline bool AllowFree(double dPriority)
 {
     // Large (in bytes) low-priority (new, small-coin) transactions
     // need a fee.
-    return dPriority > COIN * 144 / 250;
+    return dPriority > AllowFreeThreshold();
 }
 
 /** Fake height value used in CCoins to signify they are only in the memory pool (since 0.8) */
diff --git a/src/wallet.cpp b/src/wallet.cpp
index ec439c5aad..5aea9881cd 100644
--- a/src/wallet.cpp
+++ b/src/wallet.cpp
@@ -28,6 +28,8 @@ using namespace std;
 CFeeRate payTxFee(DEFAULT_TRANSACTION_FEE);
 unsigned int nTxConfirmTarget = 1;
 bool bSpendZeroConfChange = true;
+bool fSendFreeTransactions = false;
+bool fPayAtLeastCustomFee = true;
 
 /** 
  * Fees smaller than this (in satoshi) are considered zero fee (for transaction creation) 
@@ -1382,7 +1384,7 @@ bool CWallet::CreateTransaction(const vector<pair<CScript, CAmount> >& vecSend,
     {
         LOCK2(cs_main, cs_wallet);
         {
-            nFeeRet = payTxFee.GetFeePerK();
+            nFeeRet = 0;
             while (true)
             {
                 txNew.vin.clear();
@@ -1502,7 +1504,7 @@ bool CWallet::CreateTransaction(const vector<pair<CScript, CAmount> >& vecSend,
                     break; // Done, enough fee included.
 
                 // Too big to send for free? Include more fee and try again:
-                if (nBytes > MAX_FREE_TRANSACTION_CREATE_SIZE)
+                if (!fSendFreeTransactions || nBytes > MAX_FREE_TRANSACTION_CREATE_SIZE)
                 {
                     nFeeRet = nFeeNeeded;
                     continue;
@@ -1628,6 +1630,12 @@ CAmount CWallet::GetMinimumFee(unsigned int nTxBytes, unsigned int nConfirmTarge
 {
     // payTxFee is user-set "I want to pay this much"
     CAmount nFeeNeeded = payTxFee.GetFee(nTxBytes);
+    // prevent user from paying a non-sense fee (like 1 satoshi): 0 < fee < minRelayFee
+    if (nFeeNeeded > 0 && nFeeNeeded < ::minRelayTxFee.GetFee(nTxBytes))
+        nFeeNeeded = ::minRelayTxFee.GetFee(nTxBytes);
+    // user selected total at least (default=true)
+    if (fPayAtLeastCustomFee && nFeeNeeded > 0 && nFeeNeeded < payTxFee.GetFeePerK())
+        nFeeNeeded = payTxFee.GetFeePerK();
     // User didn't set: use -txconfirmtarget to estimate...
     if (nFeeNeeded == 0)
         nFeeNeeded = pool.estimateFee(nConfirmTarget).GetFee(nTxBytes);
diff --git a/src/wallet.h b/src/wallet.h
index b692ad056b..0244ce2368 100644
--- a/src/wallet.h
+++ b/src/wallet.h
@@ -32,6 +32,8 @@
 extern CFeeRate payTxFee;
 extern unsigned int nTxConfirmTarget;
 extern bool bSpendZeroConfChange;
+extern bool fSendFreeTransactions;
+extern bool fPayAtLeastCustomFee;
 
 //! -paytxfee default
 static const CAmount DEFAULT_TRANSACTION_FEE = 0;