[vtkusers] vtkGraph | setting an edge / vertex' label/weigth

[jelle]

The subject line pretty much says it all...
The new graphing API in VTK is really a great addition, but I haven't managed to
figure out how to set a label or weight to an edge or vertex.

Both 
grv.SetEdgeColorFieldName( 'edg_color' )
and
grv.SetEdgeWeightField('edg_weight')
and 
grv.SetLabelFieldName('edg_label')

Give a hint of an API for this, but I would't know how to set / get the color,
weights & labels...

Any clues would be much appreciated!

thanks,

-jelle