Emoji breaks cursor position and blocks backspace

[o-sdn-o]

In WSL, pasting the 'family' emoji via the Emoji Picker (Win+'.') misplaces the cursor position and blocks backspace.

Repro:

1. Run WSL profile in Windows Terminal
2. Run edit
3. Press Win+'.' for Emoji Picker
4. Paste the 'family: man, woman, girl, boy' emoji and press Esc
5. Check the cursor position and whether the backspace is working

Tested on Win11 and Win10.

https://github.com/user-attachments/assets/cbd3ffb7-c493-41c1-b431-4bae70685d53

[lhecker]

You've changed this setting, right?

[o-sdn-o]

This behavior occurs despite the fact that 'Grapheme clusters' is set in the settings.

https://github.com/user-attachments/assets/f747610d-646c-46e4-ad7d-9fa9485bcf85

[o-sdn-o]

This only happens under WSL. Only with the native Linux binary, only when using the Emoji Picker (Win+'.').

Additional observations:

• The emoji picker doesn't work for edit.exe (win32 binary) running under WSL.
• When pasting these emoji '👨‍👩‍👧‍👦👨‍👩‍👧‍👦' from the clipboard, everything works as expected (no issues).
• With word wrap enabled (Alt+Z), everything works as expected (no issues).
• Resizing window or pressing 'Home' then 'End' restores backspace functionality and cursor position.
• This behavior does not occur when using vtm -r wsl->edit (possibly due to the different TSF/IME backing in vtm and WT).
• This behavior occurs when using WT->vtm --tui -r wsl->edit.
• When using conhost (conhost->wsl->edit), backspace also stops working after picking such emoji (not to mention that it doesn't support grapheme clusters).
• Tested with latest WT (built from current main, x64).

[o-sdn-o]

Repro on post-quantum hardware (my iron is quite slow, allowing me to catch issues related to timeouts):

• Split the grapheme cluster 👨‍👩‍👧‍👦 into two parts:

  👨‍👩‍👧‍
  

  and

  👩
  

• Paste the first and then the second using the clipboard.

[DHowett]

I do not believe that repro to be representative of what is actually happening.

Edit requests bracketed paste mode, and so on any conforming terminal emulator your instructions will result in \e[201~\e[200~ being inserted after the last ZWJ in the first segment and before the first code unit in the second segment.

[o-sdn-o]

Yes, this isn't the same behavior; at least the result (text) looks different visually, but after pasting both parts, backspace also stops working, and the cursor position is broken, just like in the original issue.

I don't know if this issue is reproducible on faster hardware. The code point stream from the terminal is the same whether using vtm or WT (showkey -a shows this), but with a certain actor configuration (TSF+WT+WSL+edit), the issue persists.

[o-sdn-o]

[o-sdn-o]

For repro, it is enough to paste the first part of the grapheme cluster twice using the clipboard.

👨‍👩‍👧‍

[o-sdn-o]

Edit requests bracketed paste mode, and so on any conforming terminal emulator your instructions will result in \e[201~\e[200~ being inserted after the last ZWJ in the first segment and before the first code unit in the second segment.

Edit successfully receives inserted blocks wrapped in a bracketed paste sequence and there are no issues with this. When receiving a grapheme cluster in parts, it does something wrong.