Action inside another action not working

Question

I am trying to load content before the end body tag on admin pages that have a TinyMCE editor on them. To do this I am trying to leverage two action hooks 'before_wp_tiny_mce' and 'admin_footer' but it does not seem to be working as I expected. The following is a simplified version of my code:

add_action( 'before_wp_tiny_mce', 'before_wp_tiny_mce_action' );

function before_wp_tiny_mce_action() {
    add_action( 'admin_footer', 'admin_footer_action' );
}

function admin_footer_action() {
    echo "<p>I am in the footer of an admin page with a TinyMCE editor.</p>";
}

Why doesn't this work?

Answer 1

I think I worked out the problem.

before_wp_tiny_mce_action is not an action hook called before the actual TinyMCE editor in the DOM. It is called before the script that is loaded via the admin_print_footer_scripts action. So I think the admin_footer action hook is before the before_wp_tiny_mce_action action hook so I am calling my action too late.

I am going to have to find another way of detecting if a page has TinyMCE on it before it starts writing the script.