@Fields
Unfortunately, does not works even with that Mod, but thank you for your help.
@Lynne
I've some doubts sharing the link as it's an Adult Dating (but 100% NOT porn site). But as it currently has only 2-3 fake profiles for testing, in case that you don't have moral problems for the content, the link is:
http://www.xxx24.gr/member.php?3-Rene&tab=dating#dating
The tab uses the hook: member_complete and the template hook: profile_tabs_first. I also removed from the activity tab the code that makes it presected if there is no "&tab=...." in the link.
As you can see by clicking the link, the tab opens normally as first tab, but it does not has content. Click any other tab and then back to mine and you'll see that funny issue. The content is there now. Maybe the hook: member_complete is wrong and seems that I must use another one. Don't really know.