My Macbook Pro (late 2013) running OS X 10.10.4 Yosemite, doesn't respond to Hot Corners any more. Also, if an application, for example Safari, is set to full screen, basically forming a second (or third, fourth, etc) desktop, the focus keeps stuck there. If I change (CMD-Tab) the focus back to another application, for example Mail, the screen keept showing full screen Safari and doesn't follow back to the main desktop where the Mail window is. I already tried: logging out and in the user account restarting the Finder, restarting OS X repairing rights while starting up from another partition changing Hot Corners settings, Mission Control settings deleting the Dock .plist resetting the RMC, PRAM Also: I can get back to the main screen / first Desktop with CMD-1 but going back to the full screen application only works with a 4-finger horizontal swipe. Exposé works via CTRL-F3 and 4-finger swipe down, Launchpad gesture works. Mission Control 4-finger swipe up and Show Desktop gesture do not work. I noticed Hot Corners work fine with a test account, so it must be something with this account, right? I've been at this for many hours and running out of ideas. Any thoughts? BtW I don't use a mouse or special mouse software, so that is not the problem. I do use a Wacom Pro Touch Medium.