AutomationElement.FindFirst Method

/// <summary> 
/// Find a UI Automation child element by ID. 
/// </summary> 
/// <param name="controlName">Name of the control, such as "button1"</param>
/// <param name="parentElement">Parent element, such as an application window, or the 
/// AutomationElement.RootElement when searching for the application window.</param> 
/// <returns>The UI Automation element.</returns> 
private AutomationElement FindChildElement(String controlName, AutomationElement rootElement)
{
    if ((controlName == "") || (rootElement == null))
    {
        throw new ArgumentException("Argument cannot be null or empty.");
    }
    // Set a property condition that will be used to find the main form of the 
    // target application. In the case of a WinForms control, the name of the control 
    // is also the AutomationId of the element representing the control.
    Condition propCondition = new PropertyCondition(
        AutomationElement.AutomationIdProperty, controlName, PropertyConditionFlags.IgnoreCase);

    // Find the element. 
    return rootElement.FindFirst(TreeScope.Element | TreeScope.Children, propCondition);
}