void PopupMenuItem_Loaded(object sender, RoutedEventArgs e)
{
_isLoaded = true;
this.Loaded -= PopupMenuItem_Loaded;
//this.SetValue(PopupMenuItem.IsVisibleProperty, IsVisible); // The IsVisible setter is only applicable in the Loaded event because the item container it targets is not accessible before that
var container = PopupMenu.GetContainer <FrameworkElement>(this);
container.Visibility = (bool)IsVisible ? Visibility.Visible : Visibility.Collapsed;
if (UseFirstItemAsHeader && this.Items.Count > 0)
{
FrameworkElement element = this.Items.First() as FrameworkElement;
this.Items.Remove(element);
// Use first child as header if the latter is not assigned
this.Header = element;
this.UpdateLayout();
}
}
