This is ace fun! The hold is very useful and the swing slider behaviour makes more sense now.
I have a suggestion regarding the gate sliders. At the moment you have to click the button to display the slider, move the mouse over the slider to adjust the value, then click the slider to accept the value. I think it would feel much nicer if you could click and drag on the button to change the value and then release the button to accept it. Perhaps a right-click mid-drag could cancel the operation?
Having said that, I know that GUI code is a huge PITA so if you can't be bothered I won't think any less of you.
