Connecting/unconnecting to external monitor makes app windows change shape and move

I have a 15" Macbook Pro. I often use it with an external monitor or projector - sometimes in mirrored, sometimes in non mirrored . Whenever I connect or disconnect a monitor, App windows such as powerpoint shrink down to a small size, and Acrobat windows shrink to just the title bar, and some windows are off the screen and the only way that I can get them to show is to restart the app or do Save As (if I can) which brings the window back on the screen so I can have the dialogue box. This is really annoying.

Any thoughts on solving this. What I would like is a way to gather all the app windows onto whatever screen real estate is showing.

Paul