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

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 form. The code is as follows:

 private void btn_AddCat_Click(object sender, EventArgs e)
        {
            this.Invoke(new MethodInvoker(() =>
            {
                form_NewCat NewCatForm = new form_NewCat();
                NewCatForm.Show();
            }));

          开发者_如何学C  MessageBox.Show("Oops!");            
        }

The problem is, when the new form is launched, I want execution of the code behind the main form to pause at that point until the new form is closed. As an example, in the above code, I do not want 'Oops!' to get printed until the new form is closed. How can I achieve that?

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Change the line

NewCatForm.Show();

to

NewCatForm.ShowDialog();

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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.

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Simply change Show to ShowDialog; this also let's you get a return value to indicate whether the form considered itself exiting with a specific status (ok, cancel, etc).

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You want a modal dialog and I think you need NewCatForm.ShowDialog();