Function gtk_sys::gtk_menu_popup_at_widget

pub unsafe extern "C" fn gtk_menu_popup_at_widget(
    menu: *mut GtkMenu, 
    widget: *mut GtkWidget, 
    widget_anchor: GdkGravity, 
    menu_anchor: GdkGravity, 
    trigger_event: *const GdkEvent
)

Available on crate feature v3_22 only.