Fixed scrolling bugs when using rich text mode. (Work around probable bug in Qt.)

IPython/frontend/qt/console/console_widget.py

@@ -340,9 +340,13 b' class ConsoleWidget(Configurable, QtGui.QWidget):'
                 cursor.beginEditBlock()
                 cursor.insertText('\n')
                 self._insert_continuation_prompt(cursor)
-                self._control.moveCursor(QtGui.QTextCursor.End)
                 cursor.endEditBlock()
 
+                # Do not do this inside the edit block. It works as expected
+                # when using a QPlainTextEdit control, but does not have an 
+                # effect when using a QTextEdit. I believe this is a Qt bug.
+                self._control.moveCursor(QtGui.QTextCursor.End)
+
         return complete
 
     def _get_input_buffer(self):
@@ -714,10 +718,12 b' class ConsoleWidget(Configurable, QtGui.QWidget):'
                         if cursor.selectedText().trimmed().isEmpty():
                             self.execute(interactive=True)
                         else:
+                            # Do this inside an edit block for clean undo/redo.
                             cursor.beginEditBlock()
                             cursor.setPosition(position)
                             cursor.insertText('\n')
                             self._insert_continuation_prompt(cursor)
+                            cursor.endEditBlock()
                         
                             # Ensure that the whole input buffer is visible.
                             # FIXME: This will not be usable if the input buffer
@@ -725,8 +731,6 b' class ConsoleWidget(Configurable, QtGui.QWidget):'
                             self._control.moveCursor(QtGui.QTextCursor.End)
                             self._control.setTextCursor(cursor)
 
-                            cursor.endEditBlock()
-
             elif key == QtCore.Qt.Key_Up:
                 if self._reading or not self._up_pressed():
                     intercepted = True

IPython/frontend/qt/console/frontend_widget.py

@@ -176,7 +176,7 b' class FrontendWidget(HistoryConsoleWidget, BaseFrontendMixin):'
         if self._control_key_down(event.modifiers()):
             if key == QtCore.Qt.Key_C and self._executing:
                 self.interrupt_kernel()
-                return True_
+                return True
             elif key == QtCore.Qt.Key_Period:
                 message = 'Are you sure you want to restart the kernel?'
                 self.restart_kernel(message)