private void Layers_CollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
{
if (e.OldItems != null)
{
foreach (Layer layer in e.OldItems.OfType<Layer>())
DetachLayerHandler(layer);
}
if (e.NewItems != null)
{
foreach (Layer layer in e.NewItems.OfType<Layer>())
AttachLayerHandler(layer);
}
UpdateMapLayerItems();
}