There is some issue with the Menus rendering. I installed the latest Unity version and it is working better but still some issue. When I click on any menu, it only shows first the frame with no content (transparent) and after some fraction of second or a second it will show the content. I am running Linux Mint. I tested on other Linux Mint machine and the menus work fine. So there is some little differences somewhere.. EDIT: I experiment with XFCE on same machine and it works ok. The issue was while using Cinnamon.
I might have a similar issue not sure. While using Ubuntu 14.04 the menus will sometimes turn and remain white. When moving around the unity3d editor the menu will remain fixed in place while the editor moves. I've attached screenshots to showcase. Not sure what other information would be relevant to report.