Can't close masteries page on OS X if 'X' button is not visible

I opened up my masteries on the OS X client, with the window off to the side. The window cannot be moved if the masteries dialogue is open, and the 'X' is out of reach, making it impossible to close the dialog. I had to force quit the client and restart. Obvious fix: Don't open masteries unless the entire LoL window is fully visible. Possible fix to make life easier for people who aren't savvy enough to avoid this inconvenience: Allow the LoL window to be moved while masteries are open.