How to add a Windowicon + Center Window? (again)

This is sort of a duplicate post because I just mentioned this in another thread, but centering a window on creation is really a matter of professionalism. It looks very unpolished for a window to pop-up in the corner of the desktop, and it looks just a bad to see it snap to the center.

But more importantly, we need a cross-platform internal solution. Hacks for specific platforms just make for messy code and more problems.