@Override public void onClick(View v) {
        mPager.setCurrentItem(mPager.getCurrentItem() - 1);
      }
PagerTabStrip is an interactive indicator of the current, next,
and previous pages of a {@link android.support.v4.view.ViewPager}. It is intended to be used as
a
child view of a ViewPager widget in your XML layout.
Add it as a child of a ViewPager in your layout file and set its
android:layout_gravity to TOP or BOTTOM to pin it to the top or bottom
of the ViewPager. The title from each page is supplied by the method
{@link android.support.v4.view.PagerAdapter#getPageTitle(int)} in the adapter supplied to
the ViewPager.

<p>For a non-interactive indicator, see {@link PagerTitleStripV22}.</p>
sample/src/main/java/android/support/v4/view/PagerTabStripV22.java