Text drawing incorrectly with certain font size and zoom combinations

I have noticed that, since upgrading from Creator 2.4.1 to 2.5, the text in the editor window is frequently drawn incorrectly (see attachment). I can't give an exact recipe to reproduce this but typically it happens when I select a line or more of text with the mouse and then scroll up and down with the mouse wheel. It may be required that the selected text be scrolled out of the visible area but I'm not sure about that.

This only seems to happen when using certain combinations of zoom and font size (as set in Preferences->Text Editor->Font & Colors. I took the attachment using Monaco size 11 with zoom=130. However, using Monaco size 11 zoom 110%, I don't see the problem. Using size 11 zoom 140% I occasionally see text that isn't quite drawn correctly but it is not as pronounced. I have the Antialias check box checked.

This happens to all kinds of text in the editor, not just comments as my screenshot might suggest.

In all cases, activating another application causes Qt to update and redraw the text correctly.

A colleague of mine was able to reproduce the same thing on his machine. We are both using Creator 2.5 on Mac OSX 10.6.8 and using the same font settings I mentioned above. I haven't been able to reproduce using Creator 2.5 on Windows using several combinations of size/zoom with either Courier nor Arial.