Dark widget foreground

I would like to report a strange behavior that I get in our QT application. Our application has a central table, and sometimes it happens that this table is black! A window refresh, a focus on it, (sometimes) fix the issue, and everything appers as expected.

Steps to reproduce:
Moreover, I can reproduce the error with latest QT Designer version (5.1.1), provided with QT Commercial SDK. Navigating to Form -> View Code... and hitting CTRL+F to search a text in the generated code (or with the menu button), the area become black!

I've attached a screencast that shows the issue.