How to create dynamic popup menus in a gtk application

Hi,

I am currently about to migrate Gnome Commander from the very
deprecated GnomeUIInfo to GtkUiManager with the help of this document
https://developer.gnome.org/gtk2/stable/migrating-gnomeuiinfo.html

This worked out for the toolbar and also for a static popup menu.

What I am missing is how I can create dynamic popups. How is that
solved using GtkUiManager and GtkActions? Unfortunately in the
migration guide above this part is missing.

Can anyone here kindly point me to a simple example how a dynamic popup
would be created in Gtk in C/C++? In particular, I am talking about a
popup menu where its entries depend on the file which is clicked on in
the file manager.

Thank you very much and all the best
Uwe