I'm adding a OpenGLWidget to a QMdiSubWindow .

QMdiArea already contains other QGraphicsViews.

When calling setWidget(...), the QMainWindow will flash off/on.

This is done in qwidget.cpp in setParent(...) line:10531 when the next 2 lines are executed

at line 10698:

newtlw()->destroy();

newtlw()->create();

This never happened in previous versions.