private void HanghoabarButtonItem_ItemClick(object sender, ItemClickEventArgs e)
{
using (var f = new HanghoaForm())
{
f.ShowDialog();
}
}
private void hanghoaToolStripMenuItem_Click(object sender, EventArgs e)
{
//using (var form = new HanghoaForm())
//{
// form.ShowDialog(this);
//}
var form = new HanghoaForm();
form.MdiParent = this;
form.Show();
}