Just tested reducing mixes and the pixel-mad window doesn't change...
So your only option at the moment is to move the pixelmad window to the very top of the screen ad expand it as much as possible to access the DMX button - or change screen resolution to allow you to see more of the window...
You could also do this by remote desktop and change the screen resolution remotely to enable DMX
Currently there is no other method of conrol to enable pixel-mad DMX.
Let me know how you get on...
Simon