ENH: Added GetName and GetLocation methods to vtkInformationKey.  This will allow keys in a vtkInformation instance to be displayed by name at runtime.

Added label_text for things like "Element Variables" and "Node Variables". Much more intuitive for our users than "Point Arrays"

redo mouse interaction test so that the render window we're interacting in is the same size on all platforms

toggling the visibility of a data object from the source list window should not draw that data object as the current one