code: func (u *UserInterface) actualScreenScale() float64 {
  	// Avoid calling monitor.GetPos if we have the monitor position cached already.
  	if cm, ok := getCachedMonitor(u.window.GetPos()); ok {
  		return u.getScale() * devicescale.GetAt(cm.x, cm.y)
  	}
  	return u.getScale() * devicescale.GetAt(u.currentMonitor().GetPos())
  }
docs: // actualScreenScale must be called from the main thread.