Called by StyledText to add itself as an Observer to content changes.
See TextChangeListener for a description of the listener methods that
are called when text changes occur.
<p>
@param listener the listener
@exception IllegalArgumentException <ul>
<li>ERROR_NULL_ARGUMENT when listener is null</li>
</ul>
Called by StyledText to add itself as an Observer to content changes. See TextChangeListener for a description of the listener methods that are called when text changes occur. <p>
@param listener the listener @exception IllegalArgumentException <ul> <li>ERROR_NULL_ARGUMENT when listener is null</li> </ul>