Support for multiline indentation

[liltrendi]

Overview

Closes #110.

Normally, editors do support indentation based on where the cursor is positioned at:

• If the cursor is at the start of the line, pressing TAB should add an indent from the beginning of the line
• If the cursor is anywhere else within the line, pressing TAB should add an indent from the current cursor position
• If there is a specific block of text highlighted, pressing TAB should add an indent relative to that text selection
• SHIFT+TAB should do the inverse of all the operations mentioned above
• Finally, selecting multiple lines and pressing either TAB or SHIFT+TAB, should work as explained above for the lines selected

This PR aims to implement this feature in a simple way.

Demo

Screen.Recording.2025-05-24.at.17.50.50.mov

[lhecker]

I'm unfortunately not sure if we can merge this in the current state. I apologize for that. 🙈

Aside from the issues I mentioned, I believe this needs some polishing, because it's currently significantly larger than it likely could be. I have a strong gut feeling that the feature can be implemented in around 100 lines of code with a general approach that's similar to the existing code.

[AmirTallap]

Well done, thanks!

[liltrendi]

I'm unfortunately not sure if we can merge this in the current state. I apologize for that. 🙈

Aside from the issues I mentioned, I believe this needs some polishing, because it's currently significantly larger than it likely could be. I have a strong gut feeling that the feature can be implemented in around 100 lines of code with a general approach that's similar to the existing code.

Please have a look; refactored the implementation with a leaner approach & added multi-line support. Thanks!

[lhecker]

I'll review it again once I get a chance. 🙂

[liltrendi]

@DHowett requesting extra eyes on this 👀 would be nice early on so as to alleviate frequent conflicts.

[lhecker]

I'll go through this PR after #397 merges, as it introduces the ability to group multiple changes into a single undo. This will be very useful for this PR as well.

[DHowett]

thanks so much both of you for doing this!

[liltrendi]

LFG 🚀 thanks @lhecker @DHowett