In Ubuntu 14.04 and 15.10 with A10 (Radeon HD7660) and Intel i5 (Integrated Graphic) respectability, the ui of VirtualBox and Skype are not rendered rightly after sometime.
I researched and discovered that both use QT for their user interface. I do not know if this is the problem.
I install Gnome Shell and the issue continue.
DragonDisk has the same problem. It uses QT, too.
If you run sudo service lightdm restart and all are rendered rightly. But all the applications are closed. This is not practical.