Question

How to top one form on another in C#?

Answer 1

you put this in Form 2

 public delegate void CheckedEventHandler(bool val);
 public event CheckedEventHandler Checked;

and on event Click OK on FORM 2

if (Checked != null) 
    Checked(yourvalue); // bool value

and now in FORM 1

using (Form2 form = new Form2())
{
form.Checked += form2_Checked;
form.ShowDialog();
form.Checked -= form2_Checked;
}

void form2_Checked(bool val)
{
// do whatever you want with your value (form FORM2) set TopMost 
}