I have multiple lamps and lights in my set, but can't see all of the light/lamp controls in the light tool because the vertical scroll bar is frozen at the bottom position, and several lamp controls at the top are off screen.  After much experimenting I was able to get the light tool scroll bar to work, by dragging in another lamp from the prop content window into my scene, and then deleting that lamp.  Has anyone else experienced this error?  Is there a fix, other than the round about way I got the scroll bar to work?