gum choose: Keybindings to invert selection

[lwbt]

Is your feature request related to a problem? Please describe.
No.

Describe the solution you'd like
I'd like to have keybindings to invert (e.g. i) a selection in gum choose and to have these keybindings documented in a way that I don't need to read the source code itself (requiring understanding of how the code works).

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
#388 added the shortcut to select all or none, but my FR for a shortcut to invert was overlooked.

[caarlos0]

what the advantage of having invert selection vs select all?

it seems to me that:

• if you had invert selection, you would select the few items you don't want, then invert
• with select all, you select all, then uncheck the unwanted items

seems the same amount of keystrokes? what am I missing?

[lwbt]

It has been some time since I filed the initial FR. At first sight it looks like personal preference, even to me.

• with select all, you select all, then uncheck the unwanted items

That's correct for cases when you already know what you want. Rational use-cases.

On second thought my reasoning must have been that you start to look through a list of items, mark a few and only later realize that you need the opposite of this selection (irrational use-case if you so will, sorry if this triggers some people). Or you are in some kind of explorative / indecisive state and switch back and forth between normal and inverted until you make a decision. I sometimes find myself in such situations and I am grateful when the software has an option to perform a simple(?) inversion. I thought Gnome Nautilus / Files is one of such programs that does this, but it doesn't. Rather unrelated to this are the invert options in Gimp.

Feel free to close it if it is too complicated to implement and maintain.