I want to run some code in this context after the form created here closes.
Form1 Form1 = new Form1();
Form1.Show(); //<-After this closes, I want to run co         
        
just register for the FormClosing event of the Form
void MyClosingEvent(object o, FormClosingEventArgs args)
{
}
private void aboutToolStripMenuItem_Click(object sender, EventArgs e)
{
    Form1 form1 = new Form1();
    form1.FormClosing += new FormClosingEventHandler(MyClosingEvent);
    //Or if you have C# 2 or higher: 
    //form1.FormClosing += MyClosingEvent;