code: func (v *Menu) PopupAtMouseCursor(parentMenuShell IMenu, parentMenuItem IMenuItem, button int, activateTime uint32) {
  	wshell := nullableWidget(parentMenuShell)
  	witem := nullableWidget(parentMenuItem)
  
  	C.gtk_menu_popup(v.native(),
  		wshell,
  		witem,
  		nil,
  		nil,
  		C.guint(button),
  		C.guint32(activateTime))
  }
docs: // PopupAtMouse() is a wrapper for gtk_menu_popup(), without the option for a custom positioning function.