How to prevent tab switching on validation errors using p:tabView?

It is necessary to use binding and an ajax event whereas the form resides in the RegisterPage:

XHTML:

<p:layoutUnit position="center">
    <p:tabView id="mainTabView" binding="#{tabIndexHelper.messagesTab}">
        <p:ajax event="tabChange" listener="#{tabIndexHelper.onTabChange}" />
        <p:tab title="Startseite" id="startPage">
            <ui:include src="HomePage.xhtml" />
        </p:tab>
        <p:tab id="registrationPage" title="#{ivy.cms.co('/Translations/Registration/tabTitleRegistration')}" >
            <ui:include src="RegisterPage.xhtml" />
        </p:tab>
    </p:tabView>
</p:layoutUnit>

Backing-Bean:

private TabView messagesTab = new TabView();

    public TabView getMessagesTab () {
        return messagesTab;
    }

    public void setMessagesTab(TabView messagesTab ) {
        this.messagesTab = messagesTab;
    }

    public void onTabChange(TabChangeEvent event) {   
        TabView tabView = (TabView) event.getComponent();

        int activeIndex = tabView.getChildren().indexOf(event.getTab());

        this.messagesTab.setActiveIndex(activeIndex);

    }

Maybe there is an easier way (?) - but it worked for me.