I posted the first version of my port of Microwindows plus FLTK to Android on GitHub now:
https://github.com/ghaerr/microwindowsIt is based on Linux. You can download the package by clicking on the „Download ZIP“ button on GitHub. Rename the downloaded archive to microwindows in your home directory before using it.
In the microwindows/doc directory there is an application note that describes how to run FLTK on Android using Microwindows.
The port is based on the Allegro graphics library for Android. Microwindows got drivers based on this Allegro library and provides an X11 interface. FLTK runs based on this X11 interface provided by Microwindows.
You will have to download and install a cross-compiling environment for Android. This is described in the included application note.
The package that you can download from GitHub contains precompiled libraries of Allegro, Microwindows, Freetype and FLTK, so you do need to compile these. You just have to compile the examples and transfer them to your Android device using the run.sh script included. This will work after you installed the cross-compiling environment.
The application note further describes how you could compile these libraries on your PC, if you wanted to.
Have success with this package!
Georg