Well something like that http://r.ussell.me/LI0p that image shows my one issue. Then I have white spots and then I have the text box issue as well. Just all around randomness and I just did a fresh install of Mountain Lion and the issue was already happening by the time I installed Microsoft Office.
I tryed deleting Spotify but that didn't work but it could be way deeper something Spotify did when first ran. Their apps are notoriously clunky just go look at their support forums I've had many issues with the iOS app not many with the desktop.
This is my Launchpad http://r.ussell.me/LIS7 I haven't installed anything else like Facebook Video or anything. I think I'm gonna try my moms macs for a while and see if I have the same issue. I'm using 2010 17" Macbook Pro 1920x1200 if that makes any difference.
Are you using a Logitech keyboard? If so, check the Logitech preference pane for any special settings for Safari. If there are none, or if you're not using a Logitech input device, remove the software according to the developer's instructions (not by dragging something to the Trash.) If that doesn't work, remove the Spotify software the same way.
I use a logitech mouse. I unistalled the logitech software with the logitech uninstaller. And I have uninstalled the Spotify software following this method (bar the last step) http://www.spotify.com/us/help/faq/tech/reinstallation-of-spotify-osx/
I have restarted my mac after uninstalling the programs but it has not fixed the problem.