将此代码放入函数中。php主题（或子主题）文件。它使用jQuery在类别上方添加一个新框div (<div id="categorydiv" class="postbox " >).

add_action( \'admin_footer-post.php\',     \'wpse_99252_add_categories_title_attribute\' );
add_action( \'admin_footer-post-new.php\', \'wpse_99252_add_categories_title_attribute\' );

/**
 * Add a title attribute to categories box in the Post Editor.
 */
function wpse_99252_add_categories_title_attribute() { ?>
    <script type="text/javascript">

        // Setup tool tip box.
        jQuery( "#categorydiv" ).before( \'<center id="categorydiv-tooltip">Which catgeory should I post in?</center>\' );

        // Style it. Hide it.
        jQuery( "#categorydiv-tooltip" ).css( {
             \'margin-bottom\': \'4px\',
             visibility: \'hidden\'
             // Add more styles here.
        } );

        // Display or hide tool tip box on mouse events.
        jQuery( "#categorydiv" ).mouseenter( function() {
            jQuery( "#categorydiv-tooltip" ).css( \'visibility\', \'visible\' );

        } ).mouseleave( function() {
            jQuery( "#categorydiv-tooltip" ).css( \'visibility\', \'hidden\' );
        } );

    </script>
    <?php
}