// Set up the conditions for finding the text control.
PropertyCondition documentControl = new PropertyCondition(
    AutomationElement.ControlTypeProperty,
    ControlType.Document);
PropertyCondition textPatternAvailable = new PropertyCondition(
    AutomationElement.IsTextPatternAvailableProperty, true);
AndCondition findControl =
    new AndCondition(documentControl, textPatternAvailable);

// Get the Automation Element for the first text control found.
// For the purposes of this sample it is sufficient to find the 
// first text control. In other cases there may be multiple text
// controls to sort through.
targetDocument =
    targetWindow.FindFirst(TreeScope.Descendants, findControl);

// Didn't find a text control.
if (targetDocument == null)
{
    targetResult.Content =
        WPFTarget +
        " does not contain a Document control type.";
    targetResult.Background = Brushes.Salmon;
    startWPFTargetButton.IsEnabled = false;
    return;
}

// Get required control patterns 
targetTextPattern =
    targetDocument.GetCurrentPattern(
    TextPattern.Pattern) as TextPattern;

// Didn't find a text control that supports TextPattern.
if (targetTextPattern == null)
{
    targetResult.Content =
        WPFTarget +
        " does not contain an element that supports TextPattern.";
    targetResult.Background = Brushes.Salmon;
    startWPFTargetButton.IsEnabled = false;
    return;
}