Borderless windowed clients always take up the entire display.

[Lowclock]

I typically play with one instance at 1920x1050 borderless windowed so its essentially full screen but not covering the task bar in v4, but in v5 this just makes a slightly aliased client that takes up the entire display. Gross.

[Lowclock]

This also results in windower UI elements being rendered correctly relative to screen dimensions, but interacting with them is as if they honor the targeted resolution specifically. For example, arcon's packet viewer buttons are at the bottom of the game window regardless, but at my resolution, I have to hover/click roughly 30 pixels above them.