* Fix incorrect saved window positions
As of however many UI PRs ago windows store their last position on the client and it re-opens windows at that position.
The issue is that the code to avoid windows being able to go off-screen was immediately bulldozing this value, at least if the x <= 0. Now we just don't run it until we have a valid measure (probably the frame after) and avoid unnecessarily having an incorrect position applied.
* Explainer
