Created attachment 113109 [details] Black unity dashboard To reproduce the bug, open Libreoffice Calc, select some cells, try to apply borders. The Unity shell becomes black, also if it's there since when you pass the mouse onto the different buttons you can see the usual suggestion for the contents.
I can not confirm with Version: 4.5.0.0.alpha0+ Build ID: 40432ac6caa478474d73786f95b808c14e106ff2 TinderBox: Linux-rpm_deb-x86_64@46-TDF, Branch:master, Time: 2015-02-03_01:24:42
This is NOTOURBUG. After seeing your screenshot it can be seen that you’re using Unity 2D – which is unsupported and unmaintained since 2012. Please upgrade your Ubuntu version.