Tree: focus not updated correctly in various cases

[bill]

ISTM focus on the tree isn't updated correctly in the following cases (or at least some of the following cases):

• focused node is deleted (by, for example, another user... and Tree receives delete notification)
• focused node's ancestor is deleted
• focused node is dragged and dropped into collapsed node, thus becoming hidden

Does focus go to "the right place" in these cases (whatever that means)? Or does it just disappear (or is that the "right thing")? Or does it move to another widget entirely, outside of tree?

Closing the ancestor of focused node seems to do the right thing:

if(this.lastFocused){
	// are we collapsing a descendant with focus?
	if(dojo.isDescendant(this.lastFocused.domNode, node.domNode)){
		this.focusNode(node);
	}else{
		// clicking the expando node might have erased focus from
		// the current item; restore it
		this.focusNode(this.lastFocused);
	}
}