[plt-scheme] scheme/gui: bitmaps in containers

Hello everyone,
I'm studying scheme at the university for a while now and I'm doing a
little game as a project.
During which I was trying to create a user menu with some buttons on a
canvas (with bitmap background). Obviously, it didn't work since the
buttons can't be created in a canvas.
So I tried to look for containers which would accept any bitmap as a
background. But I could only find (set-background-color) or similar
functions.

Any ideas?