Check if form was submitted WP API

Hi there WP forums!

I have been strugling with a problem for a few days and now I decided to ask here.

I have been following wptuts on building a custom Theme Options page with the WP API and I a trying to achieve that when the form if submitted, perform a certan action.

I have 5 “tabs” (submenu_pages) and I want to run a function ONLY when the options of the first tab are updated (when the Submit Button is clicked in the first tab).

How can I do that? I couldn’t find any hooks to serve my purpouse