Can I add tabs in the panel layout or just in jobs?

Yes you add special/unique tabs to any job in the panel.

All jobs inside a panel are just inserts (i.e references to the actual job objects).  You can "explode" any job insert to normal objects that can be individually edited.  

Note:  Once you explode an insert it no longer references the original job.

1.  Select the job insert you wish to add additional tabs, then go to menu:  Edit / Explode / All

2.  Now you can add a tab.  Type:  mtab                                 ( in the FAB 3000 command console)

Important:  Just because the "Add Tabs" is not part of the Panel menu, you can still use the command.  For a list of all commands available in FAB 3000 go to menu:  Setup / Customize...