RIDE shows a red square if you use the APL Symbols (Dyalog APL) layout and type the keystroke for <ED>

[dyavc]

Describe the issue you are having

RIDE shows a red square if you use the APL Symbols (Dyalog APL) layout

Did you connect to an already running interpreter or start the interpreter from RIDE?

Start the interpreter from RIDE.

How do you reproduce the issue?

First, configure Ubuntu 22.04 or the linux of your choice to use the APL Symbols keyboard layout in /usr/share/X11/xkb/symbols/apl

1. sudo apt install gnome-tweaks

2. Start gnome-tweaks
   a) Under Keyboard & Mouse
   Turn on "Show Extended Input Sources"

b) Press the Additional Layout options

Switching to another layout
Choose a key for this. I like to choose Left Alt (while pressed)

3. In Ubuntu settings
   Keyboard
   Under Input Sources
   Press the + button
   Press the English US button if that is your native language
   Choose APL Symbols (Dyalog APL)

4. Log out and log in again.

start ride and start Dyalog 19.0.
left alt + enter gives the red square

in a TTY dyalog, it opens the editor

Paste the contents of Help → About (Shift+F1)

IDE:
  Version: 4.5.4097
  Electron: 26.6.9
  Chrome: 116.0.5845.228
  Node: 18.16.1
  Platform: Linux x86_64
  Date: 2024-02-23 15:24:25 +0100
  Git commit: 9fb313638328832b51012bd75b2523a8d97f4509
  Preferences:{
    "defaultConfig":"v19.0",
    "kbdLocale":"en_GB",
    "keys":"{\"ED\":[\"Shift+Enter\",\"unknown\"]}",
    "presetsCreated":"[\"/opt/mdyalog/19.0/64/unicode/mapl\",\"/opt/mdyalog/18.2/64/unicode/mapl\",\"/opt/mdyalog/17.0/64/unicode/mapl\"]"
  }

Interpreter:
  Version: 19.0.48958
  Platform: Linux-64
  Edition: Unicode/64
  Date: Mar  6 2024 at 11:16:30
_

[dyavc]

alt+enter seems to insert a 0xf828 unicode character. I tried setting alt+enter in RIDE preferences as an alternate for ED, but that just inserts the f828 into the dialog.

[dyavc]

FYI, other special keys in the apl keyboard layout file.
key { [ Uf850, Uf855 ] }; // BP CB
key { [ Uf800, Uf86b ] }; // QT CA
key { [ Uf821, Uf821 ] }; // ZM, ZM put this on both, the unshifted one sometimes gets lost
key { [ Uf828, Uf829 ] }; // ED, TC
key { [ Uf886, Uf887 ] }; // TO, MO
key { [ Uf802, Uf803 ] }; // TB, BT

key <DOWN> { [ Uf81f		] };	// FD
key <LEFT> { [ Uf825,	Uf84f	] };	// PV, BH
key <RGHT> { [ Uf824,	Uf854	] };	// NX, RM
key <UP>   { [ Uf820		] };	// BK
key <DELE> { [ Uf81b, Uf812 ] };	// DK, CT
key <END>  { [ Uf80b, Uf80f ] };	// RS, RL
key <HOME> { [ Uf80c, Uf810 ] };	// LS, LL
key <INS>  { [ Uf81d, Uf813 ] };	// CP, PT
key <PGDN> { [ Uf80a, Uf80e ] };	// DS, DL
key <PGUP> { [ Uf809, Uf80d ] };	// US, UL
key <KPAD> { [ Uf859 ] };	// TL
key <KPDV> { [ Uf819 ] };	// RD
key <KPMU> { [ Uf81a ] };	// TG
key <KPSU> { [ Uf831 ] };	// LN