I was working on a sketch for an envelope editor this morning. And its barebones may be useful to others. I've put it up on github:
Picture: https://github.com/jcredland/juce-toys/blob/master/adsr_screenshot.png
Source: https://github.com/jcredland/juce-toys/
(Which replaces the bazrush github site where the call queue and a few other useful bits were stored.).