Hello! 
After the last update 5.1.151 my game don’t set fullscreen correctly. My events still the same:
Result:
I tried without the action to set fullscreen using F11, but the problem looks the same. If I move the screen of preview my game comeback to normal size without the “zoom of fullscreen”.
Another thing I noticed is that it don’t shows anymore the buttons for maximize or minimize the preview.
Thanks.