Hello,
In that case, you would have to take another approach for filtering by category which does not include modifying the querystring. You would either
develop a custom Web part or wrap two Web parts in an
Update Panel and use the KB article that Juraj provided to share information between them. The page is posting back because you are changing the URL by modifying the querystring. More information about AJAX support is
available here. Additionally, repeater and pager
update panel example. The update panel property is also available for Web part zones (/CMSHelp/index.html?webpartzoneproperties.htm).
Please let me know if you have any questions.
Best Regards,
Sandro Jankovic