private void RemoveVMGroup(object selectedItem)
        {
            VMGroup group = this.SelectedItem as VMGroup;

            vmModel.RemoveGroup(group);
            group.Save();
        }
        private void CreateVMGroup(object selectedItem)
        {
            VMGroup parent = selectedItem as VMGroup;

            if (parent != null)
            {
                VMGroup newGroup = vmModel.CreateGroup(parent) as VMGroup;
                parent.Save();
                parent.IsExpanded     = true;
                newGroup.IsActive     = true;
                newGroup.IsInEditMode = true;
            }
        }