1: GMR_A[wram,ptr1] -> Surface 1
2: GMR_B[wram,ptr2] -> Surface 2
3: GMR_C[wram,ptr3] -> Surface 3
4: FBGMR            -> Surface 4

int SVGA_focus(wram_ptr, w, h, bpp); -> GMR id, surface id



3D:
	SID = focus(dst_surface);
	render -> surface SID

Flip or update:
	SID = focus(wram_ptr)
	SVGA3dCmdSurfaceCopy: SID -> 4
	(if cursor && sw cursor) wait
	                         sw blit vram
	                         cmd update

256 or gamma:
	sw blit + cmd update