As mentioned (here)[http://stackoverflow.com/a/27921408/2385479], when on the table structure page and clicking (at least) the Primary or Unique actions, the page should refresh to show that they are now grey. Doing so will also fix another minor annoyance, in this case the slider doesn't automatically expand (my InitialSiderState is 'open') but should.
PR: https://github.com/phpmyadmin/phpmyadmin/pull/1460
Diff:
Thanks Madhura!
Diff: