OCCT viewer fails to build in Debian Bookworm/Testing with gtkmm 4

[avimdev]

Viewer builds and runs correctly in a clean virtual machine running Debian Bookworm/Testing XFCE, with OCCT 7.6.3 and gtkmm-3.0-dev (both installed via apt), but does not build correctly with gtkmm-4.0-dev (installed via apt), even after modifying CMakeLists.txt to:

#set (CMAKE_CXX_STANDARD 11)
set (CMAKE_CXX_STANDARD 17)

#pkg_check_modules (GTKMM REQUIRED gtkmm-3.0)
pkg_check_modules (GTKMM REQUIRED gtkmm-4.0)

giving various gtk-related errors.
It would be very useful to have a sample of a minimal OCCT viewer in Linux using GTK4. Thank you.

System information:
Host: Debian 11 stable, XFCE, running on Thinkpad x250
Virtualization Software: Virtual Machine Manager with default configuration