I planned to create binding for gtk3 but I'm soonly defeated by the complexity of it. So I decided to create a binding for Iup. As I don't have h2def on my build I done this completely by find and replace function of JEdit. I came from Free Pascal and my knowledge about GM2 is very limited so it's just Alpha quality. But you are free to modify and extend it. I don't know much about licensing so after a while searching I think I will release my work as public domain. I wanted to host it on sourceforge but I can't register because they ask for my company, my job title... these things that I don't know how to answer. I'm a farmer which programming hobby. I don't have any company or employer. So I picked a random online file upload service I found on Google. Don't know how long they would keep my file but anyway, it's here:
https://gofile.io/?c=mfjres
Things inside the controversial directory are what I deemed as incomplete. But at least I could got the message.mod example from the test directory to compile and run fine on my computer.
p/s: before you test it please install Iup first and properly add it to ld.so.conf. I have some trouble with optional return from GM2 as this feature is new to me. If you use a procedure without the need for return value feel free to modify iup.def to make the return type optional. Regards.