Octave does not find fltk as a graphics_toolkit

[archisman-panigrahi]

Problem description

I installed GNU Octave from this repository, and the packages fltk, fltk-static from the Termux repositories. Octave does not show fltk in available graphics toolkits, only gnuplot is available.

apt search fltk
Sorting... Done
Full Text Search... Done
fltk/x11,now 1.3.5-17 arm [installed]
  Graphical user interface toolkit for X

fltk-static/x11,now 1.3.5-17 arm [installed]
  Static libraries for fltk

octave:1> available_graphics_toolkits 
ans =
{
  [1,1] = gnuplot
}

Steps to reproduce

Install GNU Octave from its-pointless repo (you may manually need to select the correct mirror, see this bug report), and then install fltk with pkg install fltk. Check the output of available_graphics_toolkits in Octave.

Expected behavior

Octave should show both fltk and gnuplot in the output of available_graphics_toolkits, and the user should be able to switch between the two.
This feature works in Octave 6.1 in my computer running Manjaro.

Additional information

$ termux-info
Packages CPU architecture:
arm
Subscribed repositories:
# sources.list
deb https://ipfs.io/ipns/k51qzi5uqu5dg9vawh923wejqffxiu9bhqlze5f508msk0h7ylpac27fdgaskx/ stable main
# game-repo (sources.list.d/game.list)
deb https://grimler.se/game-packages-24 games stable
# science-repo (sources.list.d/science.list)
deb https://grimler.se/science-packages-24 science stable
# sources.list.d/pointless.list
deb https://its-pointless.github.io/files/24 termux extras
# x11-repo (sources.list.d/x11.list)
deb https://ipfs.io/ipns/k51qzi5uqu5dgu3homski160l4t4bmp52vb6dbgxb5bda90rewnwg64wnkwxj4 x11 main
Updatable packages:
All packages up to date
Android version:
10
Kernel build information:
Linux localhost 4.9.190-perf-gb3c173e #1 SMP PREEMPT Mon Feb 1 23:49:30 CST 2021 armv8l Android
Device manufacturer:
Xiaomi
Device model:
M2006C3MI

[its-pointless]

i haven't compiled octave to graphics front end for performance reasons. This may change in future. From memory octave loses 10% performance when compiled to use it even if you don't use the graphics front end.

[archisman-panigrahi]

Unless it requires significantly more time/resources, you can consider maintaining two separate packages, one with graphics front end, and the other without it.