[Paraview] Using GUI element Scale

[Mattijs Janssens]

Hello

I am trying to write a reader for my data files. The problem is that my 
data comes from multiple files so I cannot use the existing file readers 
as example. Instead I am using a vtkdataSetSource. It all is starting to 
hang together but I have one problem:

I need to define a time step selector so

In my PVFoamReader.xml I have:

         <Scale variable="TimeStep"
             trace_name="TimeStep"
             type="int"
             label="Time step"
             range="0 1"
             default_value="0"
             display_entry="1"
             display_value="1"
             entry_and_label_on_top="0"
             help="Set the current time step."
             range_source="TimeStepRange" />

which will setup a call to GetTimeStepRange to get the max and min for the
slider.   This required the reader module to have a function of the form

     float GetTimeValueRange();

which is only allowed to return a single float.  How do I set the max 
and min
for the Scale widget using this function?

Regards,

Mattijs

p.s. is there some more documentation on writing reader modules?