Back in those early days with XFree86, it was exciting to get 2D accelerator drivers going so we could turn on "opaque window moves" in our window managers. By

Back in those early days with XFree86, it was exciting to get 2D accelerator drivers going so we could turn on "opaque window moves" in our window managers. By having the window contents "blitted" around on the card, we could finally move the actual window around instead of just a thin outline that would repaint after we stopped moving it. This required the graphics card to do it locally since there wasn't enough bus bandwidth nor cpu speed to have a software implementation copy around the window content in realtime!