Problematic commit: signallistitemfactory: Update signal prototype (be1729b3)
The commit message says:
I'm not sure this is API safe, but it is necessary if we want to support section items and canvas items.
If it's deemed API-unstable, we have to copy this object and deprecate this one.
If we would make a similar change in gtkmm, the C++ binding, it would certainly break API. The user expects to get a pointer to a GtkListItem in the signal handler, but might get a pointer to something else. Because of the name mangling in C++, it would probably also break ABI.