#3 fix crash of resize buttons on Linux Mint 18

[Stefan Sichler]

There is a serious bug regarding Linux Mint 18 Cinnamon, which I tracked down to the key_release() handler. It seems that changing the view size by pressing the "zoom in" or "zoom out" keys recurses back into key_release(). This causes the scalex and scaley setting to "explode" and an instant software crash by stack overflow.

I worked around this issue by a simple recursion check in key_release(), see the patch attached.