Creating a isocontour surface 
An other way to visualise the electrostatics grid are isocontour surfaces which 
connect all neighbouring points in the grid which have the same electrostatic 
value. We will now create such a isocontour surface:
First find the "Datasets" widget, then highlight the FDPB dataset and use its 
context menu or the menu entry "Tools->Grids->Render Contour Surface" to
create the surface.
In the now open dialog enter the value 0.01 as threshold and press "Ok".
It also possible to create multiple iso surface with different colors.