When ever I maximise a window on my second display, which is display 1 at 1280x1024, the window will leak on the my main monitor, display 2 1920x1080. It usually behaves this way but sometimes it doesn't and I can maximise a window perfectly within the display. I've also been getting a warning bubble in the taskbar since I started using windows 8 that pops up every now and then saying that the optimal resolution for this display is 2048x1142 which I can select from the windows screen resolution settings, perhaps this could be linked? As you can see in the screenshot the window is over scaled and leaves the edge outlined on the second display and if you move another window over that outline, the window image freezes multiple times in it's place.

Yes it has done before but not so frequently as steam. I recall Chrome has done it a few times but it mainly seems to effect Steam windows.