after using Ubuntu for a while and getting used to the mouse/keyboard shortcuts for window handling I imagine how great it would be to have something similar in FL Studio
Some ideas that came to my mind:
ALT: bring window to top
CTRL: send window to background (so that windows behind will be visible)
ALT + left-mouse-button: move window
ALT + right-mouse-button: resize window
Most of the time there are lots of windows open that are partially covered by each other. And bringing a window into focus I always have to take care that I don't click on a action-button by accident.