Smarty code is usually pure HTML output enriched with Smarty tags like [{blabla}] for template functionality. PHP features in [{php}] tags are correctly highlighted, as are HTML tags besides next to Smarty tags.

Whats not highlighted, are PHP tags beside Smarty tags. So this is missing IMHO:

[{if $anything}]                        // highlighted
    <h1>Anything is set</h1>            // highlighted
[{endif}]                               // highlighted
[{php}]                                 // highlighted 
    echo $anything2 ? 'set : 'notset';  // highlighted
[{/php}]                                // highlighted
<?=                                     // NOT highlighted
    $anything2 ? 'set : 'notset'        // NOT highlighted
?>                                      // NOT highlighted

It would be great, if the PHP syntax highlighted could also colorize the embedded PHP tags.