Not sure if this is the appropriate place to make feature requests but I'm not sure how to add things to Trello? I know you have a backlog of features from the kickstarter that you need to implement but I just wanted to speak up about my own priorities.
Mirror Tool
I have a character with about 30 animations for one direction which I had hoped I would be able to easily copy (and then edit) in the opposite direction just by scaling the bones to -1.0. Not getting the results I expected - everything skews very wonky, some items scale on the Y axis and some on the X?
A mirror tool inside of the editor (that would actually flip the bones without scaling them) would be INDISPENSABLE.
User Configurable Hotkeys
I've been using Spine every day for a few weeks and still get frustrated when the Space key doesnt start/stop animation playback (ie: Ableton Live, Adobe Premiere, VLC, etc...) (Also frustrated when single click on nothingness keeps a bone selected, so when I click and drag to select other bones, I just end up moving the previously selected one.)
Audio Waveform Load/Display
This is just an idea - it doesnt directly affect me at the moment, but it will in the future. For doing voice work with characters it would be useful if you could load a wave/mp3/aiff into the timeline (per animation?) so that the waveform would be visible along with the keyframes. One could then trigger keyframes at exact locations along the timeline that would synch to the sound.