Shortcode for show avatar in _sub_header.html

Is there a sortcode to show the avatar from the account that's logged in in _sub_header.html?

I tried <bx_if:show_thumbail>__thumbnail__</bx_if:show_thumbail> ( extra_sm_thumbnail.html ) but that's didn't work.

I would think you could move the thumbnail.  Did you try clearing the caches.

No there is not.

You can't just take constructors you see from one html file and expect them to work in another html file. Some of them are not global.

The bx:if constructors rely on code provided by the php script that actually processes that template. All of the constructors require supporting php code. So the ones that will work depend on what php script is parsing that template.

The _sub_header.html template is processed by inc/classes/BxDolTemplate.php which does not contain code to process that constructor. So the only way to do it would be to modify the script to provide what you need.

Can't i just put some code in inc/classes/BxDolTemplate.php so <bx_if:show_thumbail>__thumbnail__</bx_if:show_thumbail> works in _sub_header.html?

The code must stand somewhere because it's also shown in the service menu...

You can also create your own keys that you might need.  For example, I needed to hide my custom menu that replaces the standard Dolphin navigation menu; The Dolphin Menu is still needed to generate the submenu items so it is just hidden from view.  In order to be able to hide my custom menu from guest viewing, I crated a key that generates the menu and in the code it checks for guest viewing of the menu.   In the template, I just add the key for the menu. 

In my answer I did say "I would think"  So yes, you can but you need to do a little extra work; as Deano pointed out, to accomplish what you want.

This script, inc/classes/BxDolTemplate.php, must contain the thumbnail key.  Or generate a slightly different key name so you can keep up with it.  You need to add the code to that script that will generate the key because the _sub_header.html template file is parsed by BxDolTemplate.php.  Study how this is done by looking at the original thumbnail key code.