Backspace with modifiers not recognised as backspace

[fabi321]

Describe the bug
If I press backspace together with a modifier like ctrl or shift, it gets interpreted as char + modifier.

To Reproduce
Steps to reproduce the behavior:

1. Go to https://gitlab.com/kuenstler/yint-rs
2. compile and run it
3. press any modifier + backspace
4. See error

Expected behavior
In case of ctrl + backspace, it should delete unicode words. in other cases it should delete the last unicode grapheme.

OS

• Linux

Terminal/Console

• VSCode terminal: ctrl -> w, shift -> h, alt -> delete (0x7f)
• Konsole: ctrl -> h, shift -> backspace, alt -> delete (0x7f)
• Ubuntu console window: like Konsole

Language
German

[TimonPost]

I can not give you a definitive answer. Terminal input sequence codes are terrible to work with. Your language, key-board layout can play a role here. However, if you enable raw mode keep in mind any behavior like deleting the last word will not work anymore. It's your responsibility to get it to work.

[fabi321]

Yeah, of course, I implemented something that works on ctrl + backspace and it never receives any ctrl + backspace. That's some custom behavior I programmed, but it never gets to action since it never gets any ctrl + backspace.

[fabi321]

on Konsole, ctrl + backspace yields ^H (0x08), while on VSCode, ctrl + backspace yields ^W (0x17)

[TimonPost]

Hrm...

Looking through some terminal sequence documentation I see that ^ H represents backspace with the 0X08 hex code, in vt100 terminals. https://www.real-world-systems.com/docs/ANSIcode.html

I will have to dive into the ANSI code parsing of crossterm to see why this is not throwing a backspace event. It could be the case it is not yet supported in combinations with CTRL.

[fabi321]

As far as I've understood the /src/event/sys/unix/parse.rs code, the following lines in parse_event

        c @ b'\x01'..=b'\x1A' => Ok(Some(InternalEvent::Event(Event::Key(KeyEvent::new(
            KeyCode::Char((c as u8 - 0x1 + b'a') as char),
            KeyModifiers::CONTROL,
        ))))),

(line 83 and following)
are responsible for those characters

[fabi321]

I wrote a possible solution at #506 , feel free to change the style

[fabi321]

Maybe it would be a cleaner solution, if one added another KeyCode type ControlCode to raise the programmers awareness for other control codes like ^W (which I hardcoded to ctrl + backspace).

[David-Else]

Could someone fix this? It is a real show stopper for people used to the ctrl backspace for deleting a word shortcut.

[jrnxf]

Also would love to see this added! Was banging my head against the wall trying to figure out why there were no modifiers when I hit backspace until I realized this just wasn't supported lol

[TimonPost]

Closing in favor of #685.