I have been a Renoise user for a while now but have just joined the forum. Anyway, the feature I wanted to suggest is a rather simple one, but useful nonetheless. Renoise has the ability, like pretty much any other DAW, to solo and mute any combination of tracks, however it does not have any dedicated buttons to unSOLO or unMUTE all channels that have been solo’ed or muted. I realise that there is a context menu that does unmute and can be ganged to a keyboard shortcut, but perhaps both ‘unsolo all’ and ‘unmute all’ as two little buttons visible with any editor or DSP tab combination could be of great benefit.
Something very similar has been suggested here and both of these options would be great as buttons.