Url in product listing

How's that I can't see the option to list also the product URL in product listing?
How can I work around this administration limitation? What should I code in product_listing.php?

Thanks in advance for your replies!

I forgot to mention I'm still using 1.2.x version.
It would be better not to go through the overwhelming task of upgrading...
I tried once without much success due to high customization of php files in my installation.

As to upgrading, you may want to work on the upgrade in a separate folder+database so you can progressively work towards it over time, rather than have to do it all at once due to a need to protect a security problem or add some other feature dependent on the new version, etc.

As to the product-listing changes, you'll need to do many things. Here's a start:

1. in modules/product_listing.php duplicate the PRODUCT_LIST_MODEL section lines 36-40 and 100-103 for PRODUCT_LIST_URL (this will be new)
   In the second duplication, use $listing->fields['products_url'] instead of $listing->fields['products_model']

2. do similarly in includes/modules/pages/index/main_template_vars.php lines 146-148

3. do language file adds for TABLE_HEADING_URL (like TABLE_HEADING_MODEL)

4. includes/index_filters/(all appropriate files)

• duplicate the PRODUCT_LIST_MODEL sections substituting url as needed

5. add another record to the configuration table similar to PRODUCT_LIST_MODEL but renamed to match how you've used it in the other steps above.

That should get you started

Well... thank you so much!
I'l look into it and let you know...
I think I now understand how it work and I also guess I should upgrade and configure it properly.

Thank you.