I think the two parts of the problem are a) the progress bar probably shouldn't pay attention to the requested location if it is already open; that would stop the bouncing around b) we need to be less lazy about "oh, I guess I'll just open this in the center of the Display", especially when combined with "be at the top of the stack".
One option to help solve b) might be to add any dialogues that get popped up whilst there is an open progress bar to the progress bar just as secondary progress bars ... err, getting lost here... do/does/go.Adding them to the top would probably be most effective since they tend to be something that needs immediate attention before the progress can continue.
Another possibility might be to try to be more aware of layers and locations of things on-screen. We have (or at least had) a RealEstateManager to help with placing freshly opened windows. Could that (or something similar) help with placing UI items like dialogues when there are multiple items to display?
A related issue is making sure any menus that get popped up are made visible; that might be simpler since surely the major fact about a menu being pooped up is that it should be absolutely at the top of the stack?
tim -- tim Rowledge; tim@rowledge.org; http://www.rowledge.org/tim If it was easy, the hardware people would take care of it.