I just thought about a possibly really useful feature for the Ardour mixer. When you use effects (especially EQ) on a single track or bus, it is often important to be able to hear the track clearly by itself, but you still have to hear the other tracks in the background, so you can make sure the effects fit well in the mix.
For that purpose it would be awesome to have a button in every track that would reduce the volume of all the other tracks by a few dB when it is pressed. I don't really know what to call it, maybe an "Expose"-track button.
I really don't know how hard or easy this would be to program, it's just an idea.
However, thanks to Paul and the whole Ardour team for all the awesome work they have done on Ardour! Without Ardour I would not be able to do audio engineering the way I do.
PS: Please excuse my English ;-)