ARGH! My apologies, Sunthas. Using OnHide="show_window=(MainHud.Window) show_window=(MainHud.Window)" in MainHUD only works on /loadui, not on log-in, so that makes it pretty much worthless.
I was so excited that it worked that I didn't quadruple-check it.
Luckily it will still work in, for example, MainHUD.Clock. I guess since we have to mod that window to get itself to load, we can declare that the official show_window window?
(Or maybe we should use the unused "Memorized" window?)
I'll see if I can get it to work with MainHUD.visible cycling, but so far that's causing other problems.
Toss this in and your window will auto-load.