[Qt-interest] QGLWidget Starving Application Event Handler

[Marc Zinck]

I have encountered an issue where QGLWidget appears to starve the main 
application event handler.

The problem is as follows:

I create a class that inherits from QGLWidget (lets call it 
myQGLWidget).  myQGLWidget reimplements initializeGL(), paintGL(), 
resizeGL(), mousePressEvent(), mouseReleaseEvent(), mouseMoveEvent() and 
keyPressEvent().

myQGLWidget has a signal called renderingComplete() which is emited at 
the end of paintGL().  The main application connects this signal to a 
function which updates a label with the current fps value from 
myQGLWidget by calling myQGLWidget::getFps().

When I quickly interact with the myQGLWidget with the mouse the label 
updating appears blocked until I stop moving the mouse.  If I interact 
slowly, thus reducing the frequency of mouse events, the fps label is 
updated regularly.

The same behavior is observed with the example application hellogl.

The behavior appears when running the application in Windows XP 64bit 
but does does not appear when the application is run on Windows 7.

Should I be forcing an application event handling loop from inside 
myQGLWidget?

Qt Version 4.6.2

Thank you for your help,

Marc