[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/rpcconsole.h b/src/qt/rpcconsole.h
index 1370d0b103..6fbf197728 100644
--- a/src/qt/rpcconsole.h
+++ b/src/qt/rpcconsole.h
@@ -19,7 +19,7 @@ class RPCConsole: public QDialog
     Q_OBJECT
 
 public:
-    explicit RPCConsole(QWidget *parent = 0);
+    explicit RPCConsole(QWidget *parent);
     ~RPCConsole();
 
     void setClientModel(ClientModel *model);