What is custom.css in the default admin theme for?

Question

I've just been adding my own css file to the admin section of Magento 1.9, which I have done via creating a bespoke module - as suggested by other users on this site.

However, when doing so I noticed that there is a file located under skin\adminhtml\default\default\custom.css

This file contains no CSS.

My initial thought was that it could be there with the intention of developers to add bespoke css to it, but it has the following disclaimer:

 * Do not edit or add to this file if you wish to upgrade Magento to newer
 * versions in the future. If you wish to customize Magento for your
 * needs please refer to http://www.magento.com for more information.

So.. what's it for?

Answer 1

I think it is added as fallback if someone want to change/customize admin theme ...

Do not elete because its referenced here ...

https://github.com/OpenMage/magento-lts/blob/1.9.3.1/app/design/adminhtml/default/default/layout/main.xml#L84 (This was already requested @magento-LTS ... https://github.com/OpenMage/magento-lts/pull/137)