The filter element to be selected once Show is invoked. 
   Namespace:   Autodesk.Revit.UI  
  Assembly:   RevitAPIUI  (in RevitAPIUI.dll) Version: 2015.0.0.0 (2015.0.0.0) 
  Since:  2015 
Syntax
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Field Value
The default is InvalidElementId, resulting in selecting the first available (if any) FilterElement.Exceptions
| Exception | Condition | 
|---|---|
| Autodesk.Revit.Exceptions ArgumentException | When setting this property: The supplied ElementId id is not of a FilterElement. | 
| Autodesk.Revit.Exceptions ArgumentNullException | When setting this property: A non-optional argument was NULL |