Allow --ignore-immutable operations using a gesture (e.g. option/alt key)

[lgarron]

I love gg for making it easy to squash and move hunks, and use it all the time.

But I often find myself making fixups to recent main commits that are immutable. I think the safeguard is good but when I'm certain I want to perform the operation would be really nice if I had a way to to that. I think a natural way would be to:

• Enter "immutable override" mode when the option/alt key is pressed during drag/drop operations or button presses.
• Show some sort of danger warning while/right after performing such an operation (or maybe an extra confirmation dialog).
• Could also add some safeguards:
  • Require an opt-in config to allow this at all.
  • Refuse to perform operation that don't require --ignore-immutable while in this mode (to prevent developing muscle memory for always using this mode, which can result in destructive operations when not intended).

Some other ways could be to have a UI toggle, or to allow marking immutable changes as "allow modifying this until the app is closed".

I took a look at the code for implementing this, but I don't know if I can understand it well enough to contribute this.

[gulbanana]

I think this is a good idea. I haven't thought about the various gesture options yet, but some way to do this would be desirable.

[gulbanana]