I do wonder though...
What if you had to reverse a poorly done fade on a track for which you did not have the original?
For example, I have this audio from an amateur video of a band performance. The person who mastered the video started a fade way too early, something like 2-3 minutes before the end. I would like to fix this, but I don't have access to original unfaded version. What I am thinking is that I would reverse the fade temporarily, and then refade, starting 30 seconds before the end. Shouldn't be too bad, as the noisiest part I'd be fading out anyway.
Is there a way to gradually increase the volume a selected section of a waveform? Ideally, It would be something like Audacity's graphical fade in, except that you could start at 100% volume and go up from there.