[Mapguide_users] Filter Selection by Layer

[Scott Hameister]

I would like to use the API to filter a selection by a specific list of
layers...Ex: I have 8 selectable utility layers in my map, My user selects a
square area that contains 6 of these selectable layers, I want to take the
current selection (branching off from the OnSelection event) and filter the
selection down to just two or three layers...lets say Electrical Underground
(EUG), and Electrical above Ground (EAG) layers.

I found selection.GenerateFilter(layer, layerClassName) on MgSelection, but
that only allows for me to filter by a single layer...Am I missing the
obvious?