That is a good idea rfuilrez, but how do you set enter in the "To toggle broadcasting:" combo box? It seems as if it only lets me select the function keys.

I messed up on my previous try with SizeUp. This application works correctly, even moving instances from monitor to monitor and maximizing windows. I don't know what trickery are they using.

I modified the Plexer_ON.png of my plexer to display a filled circle inside the arrows when Plexer is active, it is easier to see that just the blue arrows alone.