I have attached two screen shots that illustrate the issue. To reproduce I did the following

1) Run /examples/widgets/icon -graphicssystem opengl
2) Select Cleanlooks in the View menubar
3) Move pointer to menubar and click File, View or Help.
4) These text labels, on and to the to right of the pointer cursor (this must be a clue), are now messed up.

It reproduces consistently whenever the "icons: application has been started up first time.
It only occurs after having selected Cleanlooks.
It only occurs with OpenGL graphicssystem enabled.
It only occurs the first time after the application is started up (subsequent clicks on the menubar renders it correctly).