Add Ability to Map Alt/Opt Modifier

[austinliuigi]

Is your feature request related to a problem? Please describe.

There is currently no support for binding the alt/meta/opt modifier.
I found this out just now when I tried binding it <a-l> and <a-h> to move through tabs.

Additional context

Unrecognized key <a-l> for keybinding

Currently supported keymaps

[sathishmanohar]

I would like this feature too. I have remapped my esc key to caps lock key. For scrolling previews I use <shift+j> and <shift+k>. I sometimes mistakenly type <ctrl+j> instead of <shift+j> which ends up moving commits down when in commit panel. So for history changing operations I would like to have keymaps like <alt+j> and <alt+k> to move commits.

[BrayanLope5]

Tried this same functionality but go that error as well.

[aksh1618]

I also bumped into this, and would love to see support added for this, as it'll allow me to bring in a lot of muscle memory involving alt key! For instance, coming from a lot of forgit usage, I'm very used to using Alt-j and Alt-k for scrolling supplementary buffers.

[echaya]

I need this feature as well. Today I tried to rebind <a-j> and <a-k> for <c-j> and <c-k> because the latter conflict with my nvim keybindings. Thanks in advance!

[veyzz]

up!
I also need alt modifier

[stefanhaller]

This is very non-trivial to do for us, see #3237.

[BitCalSaul]

same here, cannot make alt as a modifier.