/// -------------------------------------------------------------------
/// <summary>
/// Starts the target application and returns the AutomationElement 
/// obtained from the targets window handle.
/// </summary>
/// <param name="exe">
/// The target application.
/// </param>
/// <param name="filename">
/// The text file to be opened in the target application
/// </param>
/// <returns>
/// An AutomationElement representing the target application.
/// </returns>
/// -------------------------------------------------------------------
private AutomationElement StartTarget(string exe, string filename)
{
    // Start text editor and load with a text file.
    Process p = Process.Start(exe, filename);

    // targetApp --> the root AutomationElement.
    AutomationElement targetApp =
        AutomationElement.FromHandle(p.MainWindowHandle);

    return targetApp;
}

/// -------------------------------------------------------------------
/// <summary>
/// Obtain the text control of interest from the target application.
/// </summary>
/// <param name="targetApp">
/// The target application.
/// </param>
/// <returns>
/// An AutomationElement that represents a text provider..
/// </returns>
/// -------------------------------------------------------------------
private AutomationElement GetTextElement(AutomationElement targetApp)
{
    // The control type we're looking for; in this case 'Document'
    PropertyCondition cond1 =
        new PropertyCondition(
        AutomationElement.ControlTypeProperty,
        ControlType.Document);

    // The control pattern of interest; in this case 'TextPattern'.
    PropertyCondition cond2 = 
        new PropertyCondition(
        AutomationElement.IsTextPatternAvailableProperty, 
        true);

    AndCondition textCondition = new AndCondition(cond1, cond2);

    AutomationElement targetTextElement =
        targetApp.FindFirst(TreeScope.Descendants, textCondition);

    // If targetText is null then a suitable text control was not found.
    return targetTextElement;
}

/// -------------------------------------------------------------------
/// <summary>
/// Moves a text range a specified number of text units. The text range 
/// is the current selection.
/// </summary>
/// <param name="targetTextElement">
/// The AutomationElment that represents a text control.
/// </param>
/// <param name="textUnit">
/// The text unit value.
/// </param>
/// <param name="units">
/// The number of text units to move.
/// </param>
/// <param name="direction">
/// Direction to move the text range. Valid values are -1, 0, 1.
/// </param>
/// <returns>
/// The number of text units actually moved. This can be less than the 
/// number requested if either of the new text range endpoints is 
/// greater than or less than the DocumentRange endpoints. 
/// </returns>
/// <remarks>
/// Moving the text range does not modify the text source in any way. 
/// Only the text range starting and ending endpoints are modified.
/// </remarks>
/// -------------------------------------------------------------------
private Int32 MoveSelection(
    AutomationElement targetTextElement, 
    TextUnit textUnit,
    int units,
    int direction)
{
    TextPattern textPattern =
        targetTextElement.GetCurrentPattern(TextPattern.Pattern) 
        as TextPattern;

    if (textPattern == null)
    {
        // Target control doesn't support TextPattern.
        return -1;
    }

    TextPatternRange[] currentSelection = textPattern.GetSelection();

    if (currentSelection.Length > 1)
    {
        // For this example, we cannot move more than one text range.
        return -1;
    }

    return currentSelection[0].Move(textUnit, Math.Sign(direction) * units);
}