When %dockPosition% is Floating, this rectangle determines the size and position of the pane. Coordinates are relative to the upper-left-hand corner of the main Revit window. Note: the returned Rectangle is a copy. In order to change the pane state, you must call SetFloatingRectangle with a modified rectangle. 
   Namespace:   Autodesk.Revit.UI  
  Assembly:   RevitAPIUI  (in RevitAPIUI.dll) Version: 2015.0.0.0 (2015.0.0.0) 
  Since:  2014