This would decorate all FLTK windows with a black titlebar, making FLTK windows

seem aliens on the desktop.

My program run, but I got something similar to that.  

       [app] Running on: Ubuntu 22.04.4 LTS
       [app] Desktop: ubuntu-wayland

FLTK's OpenGL window was messed up.  It would display white (and would slowly fade to it and display ghosting).   It would also not respect the matrix transformation it seemed, as I tried to pan around the main GL window.  The bottom window (the thumbnail timeline), which is created with GLFW would work okay, thou.

I see no way that libdecor can mess up OpenGL drawing. Are you mixing headers and shared libs of distinct builds?

 

I am attaching a .png which I hope will go through.  Anyway, this was a test to see where I stand.  I will try again once the next Ubuntu LTS is released, but if you have ideas on how to fix it now, I am all ears.

libdecor is useful to create window titlebars, mostly with CSD wayland compositors, but also with SSD compositors because it does the negotiation with the compositor to ask it to draw titlebars.

Your png shows no titlebar. Is libdecor really working at all in your setup? How many top-level windows are there?

What wayland compositor do you use? If that's Ubuntu's default one, it's gnome's compositor called Mutter.

Sorry.  I used the default Ubuntu Wayland setup.  It showed a titlebar but the Ubuntu screen grabber did not save the title bar.  I had not checked the image.

I was getting the equivalent of the cairo titlebar, with a *BIG* font.

-- 
Gonzalo Garramuño
ggarra13@gmail.com