Fix window maximizing area

The title bar in the desktop client puts a 4px top margin on the draggable area to allow users to resize the window when not maximized. One unfortunate side-effect of this is that this region can no longer be used to maximize the window. If I wanted to quickly drag the window away or restore it, for most applications I could simply slam the mouse pointer to the top; but that doesn't work here.

I propose changing this margin to 0 when the window is maximized to fix this behavior. I have written a basic MVCE demonstrating this fix, here: https://gist.github.com/thebluefish/14fcb76d630ea620f0b271a02c007077