@Override
	protected boolean onRequestFocusInDescendants(int direction,
			Rect previouslyFocusedRect) {
		int focusableScreen;
		if (mNextPage != INVALID_SCREEN) {
			focusableScreen = mNextPage;
		} else {
			focusableScreen = mCurrentPage;
		}
		getChildAt(focusableScreen).requestFocus(direction,
				previouslyFocusedRect);
		return false;
	}
Gets the value that getScrollX() should return if the specified page is
the current page (and no other scrolling is occurring). Use this to pass
a value to scrollTo(), for example.

@param whichPage
@return
app/src/main/java/pro/alexzaitsev/freepager/library/view/core/VerticalPager.java