An annoying restriction of the Joomla! framework: in full article view the component header disappears.
To get around it we used to create modules turned on just for that specific menu item - this becomes rather tedious.
So, here is a simple hack to add an extra item_header to an article, which shows up in full view only. 

We have to modify only two files:

•  /components/com_content/content.php
• /administrator/components/com_content/content.xml

You can set item_header in the Content Item Edit window (Parameters Tab).
It gets styled by .componentheading.

   content.php:

find line 1591, which looks like:

    // if a popup item (e.g. print page) set popup param to correct value
    if ( $pop ) {
        $params->set( 'popup', 1 );
    }

right below, add the following snippet:

     // R3D Hack - Writes a title header that shows only in full article view
        echo '<div class="componentheading'. $params->get( 'pageclass_sfx' ) .'">'. $params->get( 'item_header' ) .'</div>';
    // HACK R3D end

That's it for this file.

Now let's change our backend XML file:

  content.xml:

on line 13 you will see:

        <param name="item_header" type="text" size="35" default="" label="Titel Header" description="A titel header that shows only in full article view" />

again, add below this line: 

        <param name="pageclass_sfx" type="text" size="20" default="" label="Page Class Suffix" description="A suffix to be applied to the css classes of the page, this allows individual page styling" />
        <param name="@spacer" type="spacer" default="" label="" description="" />

 The second param is optional - it adds a space below...