[Qt] make most Windows appear centered on main GUI

- remove default value for parent variable in dialogs, which should appear
  centered over main GUI and pass appropriate value
- add some addition NULL pointer checks

1 files changed, 1 insertions, 1 deletions

diff --git a/src/qt/editaddressdialog.h b/src/qt/editaddressdialog.h
index a448c4b23f..6910c667cd 100644
--- a/src/qt/editaddressdialog.h
+++ b/src/qt/editaddressdialog.h
@@ -31,7 +31,7 @@ public:
         EditSendingAddress
     };
 
-    explicit EditAddressDialog(Mode mode, QWidget *parent = 0);
+    explicit EditAddressDialog(Mode mode, QWidget *parent);
     ~EditAddressDialog();
 
     void setModel(AddressTableModel *model);