Borders of the docextrapanes focused tab are hardcoded to grey

The color of the borders of the tabs on the bottom of the page (comments, attachments, history, etc) are controlled by the @xwiki-border-color variable.

However, when a tab is active, the color is still grey.

• how to reproduce
• load a page
• click on a tab and display it
  • don't click elsewhere just yet

Expected result:

• the border around that tab is either the color of @xwiki-border-color or a variation of it

Actual result:

• the border around that tab seems to be always the same grey, until you click elsewhere (which keeps it active but not focused anymore)
  Here's a screenshot from an example where @xwiki-border-color is purple:
  
  vs.