When the user get back to the page or taskflow that contains the af:panelTabbed, the last tab opened will be shown instead of the first tab.
If you want to show always first tab as "opened", there is a couple of parameters at the af:showDetailItem that will help us.
This is a sample code that will make the trick:
<af:panelGroupLayout id="pgl1" layout="vertical">
<af:panelTabbed id="ptab1" position="above">
<af:showDetailItem text="First" id="sdi1" persist="disclosed" disclosed="true"/>
<af:showDetailItem text="Second" id="sdi2" persist="disclosed" disclosed="false"/>
<af:showDetailItem text="Third" id="sdi3" persist="disclosed" disclosed="false"/>
</af:panelTabbed>
</af:panelGroupLayout>
Check ADF Tag Library
Big thanks to my co worker María for finding the solution :-)
Download sample project