That is a great idea! Even greater would be to extend this to a consistent way to manage windows whose title bar is above to upper screen edge.

Both Windows and Mac OS try pretty hard to avoid this, but with two monitors it happens every now and then--especially when unpluggin/plugging the secondary monitor.

Without the title bar, it can be really hard to get the window back on the screen. Usually involves, if possible, resizing the window so it shows on both screens or unplugging/re-plugging the secondary monitor.