QMainMenu behaves weirdly if QVTKWidget is the central widget of QMainWindow

Ok it took me a while to track this down, but I have no idea how to resolve it.

The main menu in my Qt/vtk application is behaving weirdly. Clicking behaviour on the menu is as follows:

First click: pop down
Second click: pop up
Third click: does nothing
Fourth click: pop down again

Now this wouldn't be that bad, but the problem is that the states are remembered. So if the user clicks the menu twice -- i.e., closes it manually -- the next click on the menu bar will not do anything, even if he used other GUI element in between. This leads to an annoying user experience.

I created a minimal failing example:

#include <QAction>
#include <QApplication>
#include <QLabel>
#include <QMainWindow>
#include <QMenu>
#include <QMenuBar>

#include <QVTKWidget.h>

int main(int argc, char** argv)
{
  QApplication app(argc, argv);

  QMainWindow mainWindow;
  QMenu *menu = mainWindow.menuBar()->addMenu("TestMenu");
  QAction *action = menu->addAction("TestAction");

  // Setting the central widget to QVTKWidget, produces a weirdly
  // behaving menu bar:
  //   First click: pop down
  //   Second click: pop up
  //   Third click: does nothing
  //   Fourth click: pop down again
  mainWindow.setCentralWidget(new QVTKWidget());

  // Setting the central widget to any other QWidget, like QLabel, produces a
  // normally behaving menu bar:
  //   First click: pop down
  //   Second click: pop up
  //   Third click: pop down again
  // mainWindow.setCentralWidget(new QLabel("TestLabel"));

  mainWindow.show();

  return app.exec();
}

If the QLabel-central-widget is commented in, and the QVTKWidget-central-widget is commented out, the menu is behaving normally.

Any ideas what to do next to resolve this?

Solution

Bug is not occuring any more on Qt 5.4.1 and vtk 6.2.0.

(vtk bug tracker link: http://www.vtk.org/Bug/view.php?id=15013)