Retrieves the plain text of the range.
Assembly: UIAutomationProvider (in UIAutomationProvider.dll)
respects both hidden and visible text.
If maxLength is greater than the length of the text span of the caller, the string returned will be the plain text of the text range.
will not be affected by the order of endpoints in the text flow; it will always return the text between the Start and End endpoints of the text range in the logical text flow order.