Hey there! Thanks for this handy little tool!
I've two minor usability requests:
1) It would be great to have an angle selection element like in photoshop to chose the emitting direction. You could have an input next to it and a spread-slider (that would tell you the random min/max from the original angle). The spread could be also visualized in the element.
2) when sliding the min-slider of each effect higher then the max slider, the maxslider should automatically move with the min slider. This would come in handy!
I'll think about more usability thinks once I'm back on my PC (or when you'll port it to MacOS) ;)
Thanks!