Windowed Size Acting Strangely

So, it used to be the case that if I entered fullscreen, when I exited it, the window went back to the size it was before entering fullscreen

Now, when I exit fullscreen, the window is set to the full resolution of my desktop (Currently 1920 x 1200)

I can resize it back down by dragging the corners, as always – 

– but then if I enter fullscreen again, when I exit again it's back to the full resolution of my desktop

This is incredibly inconvenient and I can't figure out how to get it to go back to its old, expected behavior

Any thoughts?