When you add PHP code to be rendered with this plugin, you must in source version of the editor enter <?php and ?> to mark the PHP code, but you must use exactly signs < and >, and when you go back into the visual version of the editor, most of the code you put is simple deleted by the conversion. So, there is no way to use this plugin to get PHP code highligfhted. If you use codes for < > like TineyMCE CODE tag does, then PHP highlighting don't work, because this plugin uses PRE tag.
Any chance too see a solution for this soon?