When using GtkDropDown the signal::activate mentioned in the documentation does not work.
GtkWidget *dropdown = gtk_drop_down_new_from_strings....
// It does not work
g_signal_connect(dropdown, "activate", G_CALLBACK(signal_no_working), NULL);
// Works
g_signal_connect(dropdown, "notify::selected", G_CALLBACK(signal_working), NULL);
In the gtk4-demo examples I see that they are also using notify::selected, I am on Windows 10