Problems with windowed mode on Windows 10

[joaomarcoscsilva]

After pressing Alt+Tab on Windows 10, the game should change to windowed mode. And, in fact, it does. A thin white border appears around the game, showing that it isn't in full screen anymore. However, the window generated still occupies 100% of the screen, and it's not resizeable, so it's essentially useless. By clicking and dragging at the white borders, I can move the window around, but it's of no use, since I end up hiding part of the game. I doubt it is a problem with my screen only, since there was a ticket on the same issue on Megaglest and the sizes are probably defined by relative values rather than absolute ones.