Backspace key doesn't work on AOSP-based keyboards

[0xC0ffee1]

When using a custom keyboard (AOSP based) on an Android device (tested on Android 14), the backspace key does not function as expected. This issue does not occur when using Gboard.

Steps to reproduce:

1. Run the mock.dart example on any android device (Tested on Android 14, both physical and emulated).
2. Switch to an AOSP-based keyboard (tested on OpenBoard, HeliBoard, and GrapheneOS stock keyboard).
3. Attempt to use the backspace key.

Expected Result: The backspace key should function correctly, deleting characters as expected.

Actual Result: The backspace key does not work when using custom keyboards.

Flutter: Channel stable, 3.22.3

Demo: demo.webm

[heckmon]

terminal.onOutput = (data) async{
   if(data.contains(utf8.decode([127]))){
      terminal.buffer.backspace();
      terminal.write("\x1B[1P");
      data = data.replaceAll(utf8.decode([127]), "");
     }
 }

The terminal.buffer.backspace() moves the cursor backwards and terminal.write("\x1B[1P"); delete the character at current cursor position.

[LRSHRS]

In my case backspace does not work on iOS too. The "terminal.onOutput" does not trigger a keypress at all.

I'm using Flutter 3.27.2 with xterm 4.0.0

[oxelf]

same problem for me, on iOS the backspace key isnt triggering. also is there a way to change the keyboard thats shown on iOS by xterm? the current one doesnt even have parenthesis

[oxelf]

I have a pretty interesting use case for xterm on iOS with a local running terminal with lua, ssh, clang, wasi sdk etc so having backspace is necessary, if maybe someone from the xterm team could look at this issue with backspace on iOS? maybe @devmil?