see image for problem.
hovering mouse over missing area makes it draw.
Created attachment 6295
looks ok in pic
the pic looks ok, but on screen entire top of chromium (tabs, toolbar, bookmarks) is missing, and anything behind chromium is visible (eg the desktop).
on linux mint 17.x
Most likely a dupe of Bug 11813
The window manager is not responsible for app rendering, most likely a driver issue.