private void btnNewItem_DropDownOpened(object sender, EventArgs e) {
var mnu = new ShellContextMenu(this._ShellListView, true);
var controlPos = btnNewItem.TransformToAncestor(Application.Current.MainWindow).Transform(new WIN.Point(0, 0));
var tempPoint = PointToScreen(new WIN.Point(controlPos.X, controlPos.Y));
mnu.ShowContextMenu(new System.Drawing.Point((int)tempPoint.X, (int)tempPoint.Y + (int)btnNewItem.ActualHeight));
btnNewItem.IsDropDownOpen = false;
}