-- Fix crappy bug where input pointers are not getting set to anything
sensible for machines with no input. either that or don't compute the machine
if it wants input and isn't getting any. 

-- On middle button, separate hit test for triangle coordinates... check to see
if mouse cursor is within certain distance of this triangle. Do them backwards
just like with machine hit test. Popup window holds mixing object? 

-- Instead of replicating control widgets for every track, how about offering a
spinbutton to control what track param changes go to? 


