Get how to change selected tab

[AM]

I have 3 Tabs in a tabGroup.

When i am on the third tab and i click there on a button i want to go
back to the first tab automatically.

Code:

<tc:tabGroup id="tabs" rendered="#{controller.anotherId != 0}"
selectedIndex="#{controller.tabId}" >

                <tc:tab label="ABC">
                  </tc:tab>

                    <tc:tab label="DEF">
                   </tc:tab>

                    <tc:tab label="GHI">
                   </tc:tab>
</tc:tabGroup>

in my java-code i have getter&setter for tabId.
whith this solution, i have to click twice on the button to return to
the first tab.