[BUG] Arrow buttons don't work in Midnight Commander (Android app)

[XtraLarge]

Platform

App - Android

Server Installation Method

Proxmox (Community Scripts)

Version

App 1.3.2 (server 2.3.1)

Troubleshooting

• I have reviewed opened and closed issues

The Problem

First off — thank you for Termix and the Android app! It's genuinely great to have a proper self-hosted mobile SSH client. 🙏

I ran into a small issue: in a terminal session on the Android app, the on-screen arrow buttons don't work inside Midnight Commander (mc). Tapping up/down/left/right doesn't move the selection or navigate the panels in mc. Regular typing and other keys work fine — the problem is specific to the arrow buttons not registering within mc.

How to Reproduce

1. Open a terminal session to a host in the Android app
2. Run mc (Midnight Commander)
3. Tap the on-screen arrow buttons — the selection / cursor doesn't move

Additional Context

• Android app version: 1.3.2
• Server version: 2.3.1

Happy to provide more detail or help test a fix. Thanks again for the great work!

[XtraLarge]

I dug into this a bit and I think I found the root cause — hopefully this saves some debugging time. 🙂

Cause: the on-screen arrow buttons are hardcoded to the normal-mode (CSI) cursor sequences in app/tabs/sessions/terminal/keyboard/KeyDefinitions.ts:

arrowUp: "\x1b[A"   arrowDown: "\x1b[B"   arrowLeft: "\x1b[D"   arrowRight: "\x1b[C"

They're sent unconditionally, regardless of the terminal's cursor-key mode.

Why only mc (and other full-screen TUIs) break: terminals have two cursor-key modes (DECCKM / "application cursor keys"):

Mode	Up	Down	Right	Left
Normal (DECCKM off)	ESC [ A	ESC [ B	ESC [ C	ESC [ D
Application (DECCKM on)	ESC O A	ESC O B	ESC O C	ESC O D

mc uses ncurses, which switches the terminal into application mode on startup (smkx → ESC[?1h). Its terminfo then expects kcuu1=\EOA etc. — the ESC O … form. Since the buttons keep sending ESC [ A, mc never matches them, so the selection doesn't move. The shell (bash/readline) binds both forms, which is why arrow buttons work there but not in mc — matching the report exactly. This also affects other ncurses/full-screen apps (vim in application mode, htop, nano, dialog…), not just mc.

Fix: make the arrow buttons mode-aware. Since the terminal is rendered with xterm.js, it already tracks this — term.modes.applicationCursorKeysMode:

const app = term.modes.applicationCursorKeysMode;
const up    = app ? "\x1bOA" : "\x1b[A";
const down  = app ? "\x1bOB" : "\x1b[B";
const right = app ? "\x1bOC" : "\x1b[C";
const left  = app ? "\x1bOD" : "\x1b[D";

If the buttons send bytes straight to the SSH stream (bypassing xterm.js' own key handling), the equivalent is to track DECCKM from the output stream (ESC[?1h = on, ESC[?1l = off) and pick the sequence accordingly.

Happy to help test a build once it's patched.