Yes, It could. But we don't have simpler things than that. For this to work you would need support for different resolutions and bit depth and its switching in x server and framebufer driver. It is not there. However there is one 640x480 video plane allocated just for video output that can be overlaid over normal screen so maybe it could be reused for such 3d acceleration window. But it is a bit hackish solution and not something they will hurry to do for us. And maybe it is even not possible since this plane is in on-chip OMAP SRAM (AFAIK) not ordinary SDRAM so maybe PowerVR MBX would not be able to draw to this plane. But maybe even yes and SRAM is better for this, I don't know. Just wanted to say that there are many problems to solve.