Comment 4 for bug 880449

I'm using Ubuntu 12.04 Beta 2 and observing nearly the same behavior. Let's say windows A and B are open (but not maximized), and windows C and D are minimized. If I hit ctrl+alt+D to show the desktop (which minimizes A and B), then when I open windows C and D, they will both display the problem mentioned above (i.e., the title bars are unclickable). Note, in this case, the title bars of windows A and B are not affected. Hitting ctrl+alt+D only affects the title bars of windows that were minimized when ctrl+alt+D was hit.

If I then open all windows and hit ctrl+alt+D to close them, then the title bars of all windows go back to normal (i.e., they are all clickable again).