Appends a custom item to the list of applications that is shown
in the popup; the item name must be unique per-widget.
Clients can use the provided name as a detail for the
#GtkAppChooserButton::custom-item-activated signal, to add a
callback for the activation of a particular custom item in the list.
See also gtk_app_chooser_button_append_separator().
Appends a custom item to the list of applications that is shown in the popup; the item name must be unique per-widget. Clients can use the provided name as a detail for the #GtkAppChooserButton::custom-item-activated signal, to add a callback for the activation of a particular custom item in the list. See also gtk_app_chooser_button_append_separator().