private void treeViewTest_ItemDrag(object sender, ItemDragEventArgs e)
 {
      is_listview = false;
      treeViewTest.DoDragDrop(e.Item.ToString().Substring(10), DragDropEffects.Copy | DragDropEffects.Move);
 }

private void listViewSteps_DragEnter(object sender, DragEventArgs e)
{
     //listyiew item
     if (e.Data.GetFormats()[0].Equals("System.Windows.Forms.ListView+SelectedListViewItemCollection"))
     {
            is_listview = true;
            //The data from the drag source is moved to the target.
            e.Effect = DragDropEffects.Move;
            return;
      }
      //treeview item
      if (e.Data.GetDataPresent(DataFormats.Text))
          e.Effect = DragDropEffects.Copy;
      else
        e.Effect = DragDropEffects.None;
 }


private void listViewSteps_ItemDrag(object sender, ItemDragEventArgs e)
{
      listViewSteps.DoDragDrop(listViewSteps.SelectedItems, DragDropEffects.Move);
}

 private void listViewSteps_DragDrop(object sender, DragEventArgs e)
{
        if (!is_listview) //treeview item
        {
            //get a text of a dragged item 
            string str = e.Data.GetData(DataFormats.Text).ToString();
            //get information about hovered item 
             ListViewHitTestInfo hit_info = listViewSteps.HitTest(listViewSteps.PointToClient(new Point(e.X, e.Y)));
             //check position - must be on an item 
             if (hit_info.Location == ListViewHitTestLocations.None) return;
             ListViewItem prev_item = hit_info.Item;
              ListViewGroup group = prev_item.Group;
              int idx = group.Items.IndexOf(prev_item);
             //и так далее
       }
}