This is a lot better than having them in kmalloc memory. I'm gonna need
a way to keep track of which process owns which bitmap eventually,
maybe through some sort of resource keying system. We'll see.
It was fun for everyone to share a single framebuffer but it was also
kinda really awful. Let's move towards having a "GraphicsBitmap" as the
backing store for each Window.
This is going to need a lot of refactoring so let's get started.
