Guake gets positioned in a wrong fashion on dual monitors

[ocean]

related to this issue on guake's github: https://github.com/Guake/guake/issues/395
when the window is shown with window rect (1920,0,1920,height) which should means on the secondary monitor the window is shown on the primary monitor instead.
Also when selecting a width for guake's window which is less than 100% and we decide to center it, it will show aligned correctly (centered) on the primary screen, but aligned to the left of the secondary screen, I debugged also this, and it looks like is not guake's implementation fault, since window rects looks good, but rather some strange quirks in unity's way of positioning windows on the secondary screen.