Remap all Alt-* keymaps

[NikitaRevenco]

Alt keymappings are problematic because many people don't expect programs to create them. Often times alt keys are used for window managers or are specifically controlled by the user

This discussion happened in the past and people seem to not prefer it either: #6853

This discussion can serve as a place to brainstorm where the Alt-* keymappings should be remapped. Below is a table of all the alt keymappings.

Keybinding	Action
A-.	repeat_last_motion
A-`	switch_to_uppercase
A-d	delete_selection_noyank
A-c	change_selection_noyank
A-C	copy_selection_on_prev_line
A-s	split_selection_on_newline
A-minus	merge_selections
A-_	merge_consecutive_selections
A-;	flip_selections
A-o / A-up	expand_selection
A-i / A-down	shrink_selection
A-I	select_all_children
A-S-down	select_all_children
A-p / A-left	select_prev_sibling
A-n / A-right	select_next_sibling
A-e	move_parent_node_end
A-b	move_parent_node_start
A-a	select_all_siblings
A-x	shrink_to_line_bounds
A-J	join_selections_space
A-K	remove_selections
A-,	remove_primary_selection
A-(	rotate_selection_contents_backward
A-)	rotate_selection_contents_forward
A-:	ensure_selections_forward
A-C	toggle_block_comments
A-!	shell_append_output
`A-	`
A-u	earlier
A-U	later

I'm currently just remapping all of them under M, because M at the moment has no functionality. What are your opinions?

[sicher]

I think it would be worthwhile to look into eliminating alt-keys. Moving these into one of more minor modes would help discoverability greatly.

[NikitaRevenco]

I think it would be worthwhile to look into eliminating alt-keys. Moving these into one of more minor modes would help discoverability greatly.

Almost all Alt keymappings manipulate selections in one way or another

Maybe a good way to get started would be to take all these selection-manipulation api and put them under "Tab" key? That key doesnt seem to do anything in normal mode so it could potentially be repurposed

the reason I'm suggest Tab and not something like M, is that tab is just 1 keystroke as opposed to M which is 2 keystrokes and a bit of stretching

Thoughts?

[sicher]

The 'm' key currently contains a few "match" oriented commands, but not that many. Another option is to rename it "modify" or "manipulate" and populate it with these. The one current thing under 'm' that would not make much sense is "goto matching bracket".

[NikitaRevenco]

The 'm' key currently contains a few "match" oriented commands, but not that many. Another option is to rename it "modify" or "manipulate" and populate it with these. The one current thing under 'm' that would not make much sense is "goto matching bracket".

let me know what you think about remapping Alt-C to just D: #12072

I feel like it makes sense to make these PRs one at a time to gradually phase out Alt keys, it's hard to all agree on what should be so I'm making a pull request as a place where we can discuss that for one specific keymapping