Fix regression concerning collapsing insets after search.

To reproduce: Do a search for text in a footnote (say) that is
currently closed. Click inside the now open footnote. It will close
by itself.

We need to know whether we can go into the inset, not whether we can
edit once we're there.

src/insets/InsetCollapsible.cpp

@@ -476,7 +476,7 @@ Inset * InsetCollapsible::editXY(Cursor & cur, int x, int y)
 {
 	//lyxerr << "InsetCollapsible: edit xy" << endl;
 	if (geometry(cur.bv()) == ButtonOnly
-	    || !editable()
+		|| !descendable(cur.bv())
 	    || (view_[&cur.bv()].button_dim_.contains(x, y)
 	        && geometry(cur.bv()) != NoButton))
 		return this;