c_gtk_app_chooser_button_append_custom_item

Undocumented in source but is binding to C. You might be able to learn more by searching the web for its name.
__gshared extern (C)
void function(GtkAppChooserButton* self, gchar* name, gchar* label, GIcon* icon) c_gtk_app_chooser_button_append_custom_item;

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