gtk4-demo settings demo does not actually write settings

Steps to reproduce

1. Build gtk4-demo.
2. Run gtk4-demo.
3. Run the “settings” list view demo.
4. Click on a setting value.
5. Enter a new valid value.
6. Press ENTER.
7. Navigate away from that group of settings using the sidebar tree, then back to it again.

Current behavior

The setting has reverted to its original value. Actually, by adding a print statement, one can observe that the item_value_changed function is never even called!

Expected outcome

The setting should have changed.

Version information

• GTK 4.14.4
• Gentoo Linux
• X11
• nVidia drivers

Additional information

My guess is that notify::label is not correct in the .ui file. I assume the intention was to connect to a signal that would be emitted when editing was committed, but not on every keypress while in editing mode. I actually want exactly the same thing myself, but I haven’t figured out what that signal is. Anyway label is not a property of a GtkEditableLabel as far as I can tell, so it makes sense that it would never emit notify::label.