private ToolStripMenuItem FindMdiMenuItemOfForm (Form f)
{
// Not terribly efficient, but Mdi window lists shouldn't get too big
foreach (ToolStripItem tsi in this.mdi_window_list_item.DropDownItems)
if (tsi is ToolStripMenuItem && (tsi as ToolStripMenuItem).MdiClientForm == f)
return (ToolStripMenuItem)tsi;
return null;
}