What is this mysterious floating menu bar? Ever since I upgraded to Mavericks, a mysterious, floating menubar has appeared on my desktop. As you can see from the two screenshots below, it is there when I have many apps open and when I exit as many things as possible. It appears immediately after boot up, and interestingly, when I restart or shut down, it remains visible even after the system leaves the desktop view during the shut down process.




The bar can be moved, but not resized. Right clicking it does nothing.

Any ideas, it is quite annoying, especially when I am not using an external monitor.
I had similar problems with applications leaving artefacts on the screen with later versions of OS X. Try to quit also apps in menubar. Download something like magican, or some other program that lets you see what all is running on your mac, check activity monitor for what all is running. 

And it may be good to try to relaunch finder (cmd+option+esc, and choose finder, relaunch).