reason i ask is because i recall an issue brought on by AM(?) concerning off screen headers of frames, making it impossible to move them. As workaround all frames were forced to centre of screen. Hopefully AM can shed some more light on this matter.
Sure. And it still will. To be even more specific, the logic is basically, "If this frame is 'docked' then dock it, otherwise center it."
So if it's offscreen and floating freely in the wind, it'll recenter as normal.
PS That fix seemed to be only for custom frames then? Because I just opened 1.3b91, dragged the Impersonate window over to the 2nd monitor, closed MT. When I reopened, the Impersonate window was were I left it, off screen...