private void button6_Click(object sender, EventArgs e)
{
CloseAllChildForm();
frmsum ptype = new frmsum();
ptype.MdiParent = this.MdiParent;
ptype.Show();
}
private void toolStripMenuItem2_Click(object sender, EventArgs e)
{
CloseAllChildForm();
frmsum ptype = new frmsum();
ptype.MdiParent = this;
ptype.Show();
}