[visad] PickManipulationRendererJ3D/DirectManipulationRenderer and TextureMapping

i am using the PickManipulationRendererJ3D to get the Pixel/Element which is selected by the user with dr.checkClose and dr.getCloseIndex. This works quite good, but i cannot enable the TextureMode for this DataRendere (isLegalTextureMap() is hard coded to false).
Is there s a specific reason that they cannot work with texture mapping?
Or is there another way to get the index of a clicked element with the default renderer?

Thanks a lot,
Stefan Below