Code review comment for lp:~azzar1/compiz-core/scale-left-padding

OK, I did some thinking about this and this comes back to an idea I've had for a while but not yet had time to implement.

We need to have a concept of "overlay struts" in the EWMH or our own extension to it, eg _COMPIZ_NET_OVERLAY_STRUT. Such "struts" allow us to specify parts of the screen which are never available for output operations. That way the scale, expo and other plugins would be able to adjust all layouts to compensate for this lack of screen space on screen-level operations.

_COMPIZ_IS_NET_OVERLAY would be a property on any window which also sets _NET_WM_STRUT or _NET_WM_STRUT_PARTIAL which basically indicates that the area is reserved for both window and screen level operations. So the scale plugin would adjust its layout and dnd window accordingly