On-the-Go Multicursor Laying

[raffimolero]

MORE FORMAL ALTERNATIVE

man i should read before writing

anyway here's like a really minimal way of implementing this

Let's say I want to extract only the correct words from this sentence:

The not very quick light gray brown fox does walks plays jumps under over the big lazy ice dog.

Using a regex is impractical. copy_selection_on_next_line can't be used on one line. Ctrl+click is subject to inaccuracy. Macros can't yank them all at once. You could select every word and remove selections one-by-one, but I'd like to do the inverse.
I could use something more fine-grained.

Proposal: Cursor-Laying.
To start with a familiar idea, take C-s. It takes all your currently active selections and saves this "jump point" to a jump list, which you can later jump_back to with C-o. In the meantime, you're free to move around. This is almost what I want. I just need to add one more operation at minimum:
C-O = "jump_combine" - works just like C-o except it keeps your current selection on top of the jump. (show error if the jump is in a different file.)

This change seems simple, but is actually pretty powerful. C-s is already able to save multiple selections at once, so we can basically add as many selections as we want to a single jump point.

To put this into practice:

1. highlight The, then hit C-s. now The is in my jump list.
2. skip over not very.
3. highlight quick.
4. hit C-O. now i'm selecting The and quick with 2 cursors. It keeps my primary cursor at quick.
5. C-s to save these two cursors into one point in the jump list.
6. hit , to go back to moving with one cursor.
7. highlight brown. C-O selects The, quick, on top of my primary cursor at brown.
8. C-s and ,.
9. highlight fox. <C-O><C-s>,
10. highlight jumps. <C-O><C-s>,
11. ...
12. highlight lazy. <C-O><C-s>,
13. highlight dog.
14. C-O,
    And now, i've selected all the desired words. i can then yank them or change them or append/insert/whatever, in-place.
    hopefully you see how powerful this can be.

You may have noticed the repetition. In this state, users might bind C-j = ["jump_combine", "save_selection", "keep_primary_selection"].
But because this technique creates so many jumps in the list, we might as well give a builtin C-j => jump_append which only appends to the previous jump point instead of creating a new point each time.
The jump list caps at 30, so any previous jumps that you might have wanted could possibly just be replaced by like 25 points that just say "The", "The", "quick", "The", "quick", "brown", etc.

Would this be viable? I find myself wanting this every now and then. Decently often.
More advanced techniques could involve juggling between multiple "selection groups" which are just different jump points that were appended to. Not sure how practical that would be, so I don't consider it a priority, but it's an idea.