Writing to the Framebuffer
There may be more than just one simultaneous framebuffer per display on the hardware level.GPUs can actually scan to a display from multiple overlapping framebuffers in different resolutions and color formats in the same time. Alpha blending and rotations are often supported as well.A bit like a very large mouse cursor. In a way, mouse cursors are also framebuffers. Or like hardware video layers in the nineties.