During review of subscene review, behavior of how picking should work came up.
Pavel stated that we don't pick through transparent node.
Which is contrary to what some members of graphics team thinks is correct.
In particular SubScene is by default transparent and it is likely to be used as an overlay. If we can't pick through a transparent subscene, then it can't be used as an overlay.
Thus when implementing SubScene, I allow to pick through the subscene.
And thus introduced a contradiction in how we do things, which needs to be settled.