As far as I know both windows can be open at once but the auction house interface always appears on top of everything else. You need one of those addons that let you move it, or click the profession button twice to bring it back up.
Well i do have chars that can have both opened.I open AH and than a proffesion and they both stay
And i do have chars that opening proffesion closes AH
Found that MoveAnything addon can fixate in a place proffesions frame and allow them both to stay.This is not the solution i m looking for
I want the standart setting,where a frame will appear to he left than be followed from the next frame.Expect AH,it will close any opened but next will appear after it