QT controller not responding to clicks

[Kurt Kaufman]

For some reason, in only one of my stacks, the QT controller does not 
respond to mouseclicks. It must be something in my script, since if I 
create a new stack, add a player, associate it with a movie file, and 
start it, I can pause the movie, adjust the volume, etc. with no 
problem. I have compared the properties of the players that respond, 
and those that don't, and I don't see a difference.  Is there something 
in general that can cause this to happen?

-Kurt