How to EnablePlainTextView in XMAX

[achu]

I have the following line in HTML page when calling XMAX control. However, I didn't see the plain text icon available on my web control. Do I need to specify something else to make it work?
<param name="EnablePlainTextView" value="true" />

XMAX version 5.1
IE version: IE7

[Derek Read]

This feature is new as of the XMAX 5.5 release.