Hi Doug,
I wrote a plugin to do something very similar to what you are looking for, the core code is dead simple:
Private Sub SelectAllWithPropertyValue(ByVal CategoryName As String, ByVal PropertyName As String, ByVal Value As VariantData)
Try
Dim S As Search = New Search With {.PruneBelowMatch = False, .Locations = SearchLocations.DescendantsAndSelf}
S.Selection.SelectAll()
Dim ADoc As Document = Autodesk.Navisworks.Api.Application.ActiveDocument
S.SearchConditions.Add(SearchCondition.HasPropertyByDisplayName(CategoryName, PropertyName).CompareWith(SearchConditionComparison.Equal, Value))
ADoc.CurrentSelection.CopyFrom(S.FindAll(ADoc, False))
Catch ex As Exception
MessageBox.Show(Autodesk.Navisworks.Api.Application.Gui.MainWindow, ex.Message)
End Try
End Sub where categoryname, propertyname and value help you find all the objects you want.
I spent a lot of time trying to get this automatically triggered on user selection of either the tree or the 3D, so that it looks exactly like a selection resolution, unfortunately I ran into some limitation of the API where an event handler of the "selection change" event is not allowed to modify the selection itself (even if remove the handler, modify the selection, add the handler back)
-Nic
