macos: expander demo does not properly allocate the window size
See the screenshot attached. Also I see the following warnings on the terminal:
(gtk4-demo:26843): Gtk-WARNING **: 13:01:00.618: Allocating size to GtkMessageDialog 0x7fb872a74950 without calling gtk_widget_measure(). How does the code know the size to allocate?
(gtk4-demo:26843): Gtk-CRITICAL **: 13:01:00.618: Allocation height too small. Tried to allocate 322x112, but GtkMessageDialog 0x7fb872a74950 needs at least 322x214.
(gtk4-demo:26843): Gtk-CRITICAL **: 13:01:00.618: Allocation height too small. Tried to allocate 322x112, but GtkBox 0x7fb87190df20 needs at least 322x214.