> On the contrary. [..] Yeah, the CPU doesn't do any of that bit-blit stuff anymore. But the GPU does that constantly every frame, over-and-over again to compos

> On the contrary. [..] Yeah, the CPU doesn't do any of that bit-blit stuff anymore. But the GPU does that constantly every frame, over-and-over again to compose modern windows. I was referring to the CPU side obviously since the operation you described in the message i replied to was done on the CPU at the time. Also that plane i refer to is drawn at a later stage to composition - in fact it is used by older Windows versions (before 8) when DWM was disabled (or didn't exist, in WinXP) for the cursor, while the rest of the system did the region-based clipping approach. FWIW it is also used by Xorg nowadays for the exact same reason - and like with Windows without DWM, Xorg without a compositor still uses a region-based clipping approach to drawing but the dedicated plane for mouse cursors to display the cursor.