Aero Snap doesn't work to drag window when maximized; split panels cannot be resized

It's very annoying that I cannot drag a maximized source tree window from the top to restore it the way I do with every other window.  I haven't seen this bug since apps were first being made for Windows Vista when Aero Snap was first introduced.  Older versions of MS Office had this problem.

Also, the split panels cannot always be resized. For example, the horizontal split between the tree view and staging area is locked with the tree taking up around 70% of the view.  When I try to drag to resize it, it just snaps back to where it was and seems to maintain the ratio no matter how the window is resized.  It makes it  impossible to work with files and diffs efficiently.