Injecting JavaScript and CSS Into Magento Admin Panel Page Head
The Magento Admin panel is controlled by the Adminhtml module, which does not have a strict layout mapping. This is a problem when we want to add our own JavaScript and CSS to create a new module or improve old modules.
(This post is a developer's guide.)
For pages lacking .xml layout, the common method like the following will not work:
<action method="addJs"><script>jquery/jquery.js</script></action>[/codesyntax]Instead, we should directly inject the JS into the 'blocks' given by .php files.