Thai glitch on width of composite character

[peterjc]

Summary

Download and open http://www.cl.cam.ac.uk/~mgk25/ucs/examples/UTF-8-demo.txt and look at lines 123-130. Move the cursor about line 130 column 40, watch what is highlighted and the location (bottom right of screen). There appears to be a composite character which glitches.

Reproduction Steps

I tried this:

1. rm -rf ~/.cache/helix/helix.log ; hx UTF-8-demo.txt:130:40

2. Confirm selection is 130:40
3. Press left, highlight moves, seems to jump over a "hook" (like a vertically flipped lower case j with no dot) character that vanishes (and different background)

4. Confirm selection is 130:39
5. Press right, highlight moves, seems to jump over the "hook" character that reappears
6. Quit.

Or,

1. rm -rf ~/.cache/helix/helix.log ; hx UTF-8-demo.txt:130:40
2. Confirm selection is 130:40
3. Press up.
4. Visually the cursor moved up in the same column
5. Confirm selection is now 129:41
6. Quit

Helix log

File ~/.cache/helix/helix.log was empty.

Platform

macOS

Terminal Emulator

Ghostty 1.0.1

Installation Method

releases page

Helix Version

helix 25.1 (dabfb6c)

[kirawi]

Probably a duplicate of #6012

[peterjc]

Agreed. I was aware of the grapheme width issue from the Ghostty author’s blog posts (linked to from that issue), but hadn’t seen symptoms like this linked to it.