private void mnuViewProduct_Click(object sender, EventArgs e)
{
if (productForm != null)
{
productForm.Show();
}
else
{
productForm = new ProductForm();
productForm.MdiParent = this;
productForm.Dock = DockStyle.Fill;
productForm.Show();
productForm.FormClosing += productForm_FormClosing;
}
}
public void productForm_FormClosing(object sender, FormClosingEventArgs e)
{
productForm = null;
}