Have you ever dropped in a widget into your page, got all the options and interactions set up just the way you want it and then realized it should really be in a Widget Controller in your header. So you drag your widget up to put it in the header, only to find there is an impenetrable force field keeping your widget from where you want it to be. So, you sigh and delete your widget and configure it all again in the header?
I've done it. Multiple times.
But don't, there is an easier way. You can't just move a widget in or out of a header, but you can copy it in.