@Override public void setBackgroundColor(int color) {
    super.setBackgroundColor(color);
    if (!mDrawFullUnderlineSet) {
      mDrawFullUnderline = (color & 0xFF000000) == 0;
    }
  }
@return The current tab indicator color as an 0xRRGGBB value.
sample/src/main/java/android/support/v4/view/PagerTabStripV22.java