Blue Stork icons Calendar and Revert not supported?

[Paul van Haren]

While developing a component, we found that Blue Stork provides icons for Calendar and Revert buttons in the taskbar, but these buttons are somehow not supported by the Blue Stork template.css. Apparently, there are more unsupported icons, as there are 65 icons availble on the file system and 43 supported by the css.

1) Is there a reason for not supporting these icons?
2) Is there a propper way to include these icons, without altering the Blue Stork files?

Your inputs are appreciated!