屏幕方向orientation，竖屏Portrail，横屏Langscape，支持的屏幕方向 SupportedOrientations="PortraitOrLandscape"
启动的屏幕方向Orientations="Portrait"
OrientationChange事件重写
public About()
{
InitializeComponent();
OrientationChanged += new EventHandler<OrientationChangedEventArgs>(About_OrientationChanged);
}
void About_OrientationChanged(object sender, OrientationChangedEventArgs e)
{
if (e.Orientation == PageOrientation.LandscapeLeft || e.Orientation== PageOrientation.LandscapeRight)
{
TitlePanel.Visibility = Visibility.Collapsed; //横屏不可见
}
else if (e.Orientation == PageOrientation.PortraitDown || e.Orientation== PageOrientation.PortraitUp)
{
TitlePanel.Visibility = Visibility.Visible; //竖屏可见
}