I don't see that happening on the mac i have mavericks installed on.
Perhaps if you have a retina display that has something to do with it.
So if you go to File>New and choose a preset document size of say Web>800 x 600, you still see that same thing?
Could you post a screenshot showing the whole desktop?
What i see:
See if resetting the photoshop cc preferences makes any difference
Press and hold down the Shift+Option+Command keys and then start photoshop cc
Keep holding the keys down until you see a dialog asking if you want to delete the adobe photoshop settings file
Press Yes