Windows flicker for one frame in top-left corner

[scallyw4g]

Windows have their initial position set to 0,0 (top-left) and they flicker there for a single frame before being laid out in their actual position.

You could imagine this being fixed in a couple ways:

1. Just draw the window way off-screen on the first frame (tried this real quick, didn't work immediately with low effort)
2. Bifurcate the layout and render passes, then:
   2.a) Go back and offset everything to the correct position on the first frame (it depends on the size of the window content)
   2.b) Just skip drawing the window on the first frame.

so.. yeah.