Cannot map Ctrl-Shift-<letter>

[howard36]

Summary

I would like to create a shortcut for Ctrl-Shift-J. I've tried adding

[keys.normal]
"C-J" = "insert_mode"
"C-S-j" = "insert_mode"
"C-S-J" = "insert_mode"

to my config.toml file, but none of these seem to work.

Other key combinations like Alt-Shift-J and Ctrl-j seem to work fine in helix, just not Ctrl-Shift-<letter>. I've reproduced this issue with multiple letters (J, K, Z) and multiple terminals (Kitty, Alacritty, Konsole).

Ctrl-Shift-<letter> is properly detected by other applications on my computer (e.g. firefox), so my keyboard seems to be working fine.

Reproduction Steps

I tried this:

1. Add the above key mappings to config.toml
2. Open helix with any file (or no file)
3. Press Ctrl-Shift-J

I expected this to happen:
Helix switches to insert mode

Instead, this happened:
Nothing happens (asciinema recording: https://asciinema.org/a/RLdAHrib8PNWg3dWuSnnhDjKc)

Helix log

No new messages were logged in ~/.cache/helix/helix.log while performing the steps above.

Platform

Linux

Terminal Emulator

kitty 0.26.5

Helix Version

helix 22.12 (installed from Arch Linux repositories)

[the-mikedavis]

This is from the limitations of default terminal keyboard input. We will need to implement+enable the enhanced keyboard protocol to be able to parse these keys accurately (#4939)

I will close in favor of #1085 which tracks this