private void galleryControlPictureList_MouseDown(object sender, MouseEventArgs e)
{
//MouseDown在Gallery_ItemClick之前
if (sender is GalleryControl)
{
GalleryControl senderGalleryControl = sender as GalleryControl;
if (e.Button == MouseButtons.Left)
{
GalleryItem senderGalleryItem = null;
GalleryControlGallery senderGalleryControlGallery = senderGalleryControl.Gallery;
&