Refresh UI With Dispatcher In Detail

I have read that this refreshes the UI but why so? I have been using this sometimes and it kinda sometimes worked but what happens in details when I execute this code below. Dispatcher invokes this empty action and thats it, there is no call invalidatemeasure() which would trigger the UI to re-measure and re-arrange and re-render inside the action. Where is here the measure and arrange process which update/refresh the UI? Whats happening under the hood?

What are the details behind this? Any help?

private static Action EmptyDelegate = delegate() { };


public static void Refresh(UIElement uiElement)
{
   uiElement.Dispatcher.Invoke(DispatcherPriority.Render, EmptyDelegate);
}

EDITED: I want to know the details why is UI rendered and what is happening in background of it. Answers like "well that triggers ui update" are not helping me or anyone else any further. It would be interesting the know the background of this and not just the basics.

Best regards,

UX Junkie