I set the workspace to the default panel set - score on left, stage on right, cast on bottom.
Whenever I hit the "Play" button on the control panel, the two panels - score/stage undock and reposition. The stage gets much larger and even goes from 50% (which I set manually) back to 100%.
Well, I figured it out.
I have some code in the prepareMovie event handler that resizes the _movie.stage.rect. When this happens the authoring tool changes.
I put in a "
(_system.environmentPropList.runMode != "Author"
and this fixed the problem. Strange, I had scripts disabled and it ran this handler anyway.