Getting features from all layers, both above and underneath map tile layers.

The original getFeatures returned the vector layers that were targeted by the mouse event, but only for those vector layers that were positioned above any map tile layer(s).  

I've adjusted getFeatures so that it continues to fetch features from all targeted vector layers, including those that lie below any map tile layer(s).  

While for my purposes I can get away with a simple className check, I'm guessing there is a better (more general) solution out there...