private void InsertToolStripMenuItem_Click(object sender, EventArgs e)
{
if (ctlMenuInsertCurrent != null)
ctlMenuInsertCurrent.Checked = false;
ToolStripMenuItem ctl = (ToolStripMenuItem)sender;
ctl.Checked = true;
ctlMenuInsertCurrent = ctl.Checked ? ctl : null;
MDIChild mc = this.ActiveMdiChild as MDIChild;
if (mc == null)
return;
mc.SetFocus();
mc.CurrentInsert = ctlMenuInsertCurrent == null ? null : (string)ctlMenuInsertCurrent.Tag;
}