A way to set Mouse focus?

I'm trying to get the mouse focus away from a Tree Control, over to a Slide that has a MouseWheel event.
Yet dcl-Control-SetFocus is only setting the keyboard focus -- any mouse wheeling is only affecting the tree.
I'm guessing that from within the TreeControl.SelChanged event, there's just no way to give up the standard Windows mouse focus.  Maybe there's a way to have a delayed invoke to fake a mouse click elsewhere?

--J

Eh, you know, I've decided I was crazy.
It would be too disconcerting to the user if for every click within the Tree, if it kept blinking elsewhere, and they couldn't mouse wheel within the tree.

So nevermind, I was an idiot!

--J