arcpy - Controlling Categories in Script Validation Tools - Expanding Groups By Default

The validation tab in your script tool properties allows you to put parameters in categories. The help states:

Put parameters in different categories. Categories are expandable window shades with a collection of parameters.

I am using the categories to organize my parameters, so I don't care about the expandable/collapsible feature; it just adds a lot of time to the user. This is all within a normal toolbox, not a script toolbox. v10.1

Does anyone know how to have these categories expanded by default?

Here is my only validation code. I am only utilizing categories. The other parts are the default.

def initializeParameters(self):
    """Refine the properties of a tool's parameters.  This method is
    called when the tool is opened."""
    self.params[0].category = "General"
    self.params[1].category = "General"
    self.params[2].category = "Inudaciones"
    self.params[3].category = "Cienegas"
    self.params[4].category = "DrenajesPrincipal"

    self.params[5].category = "DrenajesSensillos"
    self.params[6].category = "Inudaciones"
    self.params[7].category = "Cienegas"
    self.params[8].category = "DrenajesPrincipal"
    self.params[9].category = "DrenajesSensillos"
    return

Answer

This isn't possible in python, but you can by using a custom stylesheet.

1. 
   
   

   Copy "C:\Program Files (x86)\ArcGIS\Desktop10.2\ArcToolbox\Stylesheets\MdDlgContent.xsl" to the same folder as your script.

   
   


2. 
   

   Edit line 467 to remove STYLE="display:'none';", i.e. change:

   
   
   
   

   to

   
   



3. 
   
   

   Then in your script tool properties, set the stylesheet property to your edited.xsl.