void GoForward(object x)
 {
     if (Content.ActiveItem == Home && Home.CanGoForward)
     {
         Home.GoForward();
         return;
     }
     ScreenIndex  += 1;
     _goingForward = true;
     Content.ActivateItem(ScreenHistory[ScreenIndex]);
 }
 void SwitchHomeButton()
 {
     if (!Home.IsActive)
     {
         Content.ActivateItem(Home);
     }
     else
     {
         Home.GoHome();
     }
 }
 void GoBack(object x)
 {
     if (Content.ActiveItem == Home && Home.CanGoBack)
     {
         Home.GoBack();
         return;
     }
     ScreenIndex -= 1;
     _goingBack   = true;
     Content.ActivateItem(ScreenHistory[ScreenIndex]);
 }