winforms_processdialogkey_usercontrol.cs

protected override bool ProcessDialogKey(Keys keyData)  
{
    // Suppress the accept button by preventing the parent form
    // from processing the return key.
    // Return false to indicate that the key press has not been
    // handled and the child control should handle it.
    if (keyData == Keys.Return)
        return false;

    return base.ProcessDialogKey(keyData);
}