Port to Gtk 4?
So I had a quick look at the source code for this project and saw that it was still using GTK 3. This is not really a problem many apps still have to take the leap to GTK 4.
Anyway, from my quick look I thought that if it were to be ported that the best thing to do would be to pull in gtk-vnc in-tree to ease the porting process, as that library seems rather stale at the moment, and there are probobly no other users of the library anyway.
Using libadwaita instead of libhandy is probobly a given.
Then it should "only" be a matter of doing what is needed to convert to the new gtk interface. (probobly one component at a time, commenting out the that are not worked on and adding them as they are ported...).
Just a thought...