How can I make execution pause until new form is closed?

Question

I am making a Win Forms application to learn more since I don\'t have much experience with it. In my program, in the main form, I have a button. Clicking it launches another for

Answer 1

You don't need to invoke when you are in the UI thread. And you are in the UI thread in a button-click eventhandler.

private void btn_AddCat_Click(object sender, EventArgs e)
{
    form_NewCat NewCatForm = new form_NewCat();
    var dialogResult = NewCatForm.ShowDialog();
    MessageBox.Show("Oops!");            
}

You can check the dialogResult for OK, Cancel, Yes, No, etc if your form_NewCat sets this.DialogResult to any value before closing. This is the usual way to signal how the user exited the form/dialog.