Increased max width of amount field to prevent number overflow bug.

src/qt/bitcoinamountfield.cpp

@@ -197,7 +197,7 @@ BitcoinAmountField::BitcoinAmountField(QWidget *parent) :
     amount = new AmountSpinBox(this);
     amount->setLocale(QLocale::c());
     amount->installEventFilter(this);
-    amount->setMaximumWidth(170);
+    amount->setMaximumWidth(240);
 
     QHBoxLayout *layout = new QHBoxLayout(this);
     layout->addWidget(amount);