No it's not wrong. I was mistaken, didn't realize that a turbine.ui.window was already moveable if you have a title bar on it. Just my lack of experience showing threw
Sorry for leading you in the wrong direction yesterday. You were actually correct in the first place with your PositionChanged function. So make sure you change your resizeHandle.MouseUp function back to the way it was before I suggested you change it.
Hope it all works out.