[orca-list] strange behaviour with alt+shift+h, alt+shift+k and etc

[José Vilmar Estácio de Souza <vilmar informal com br>]

Hi all.
To reproduce try the following:

1. Launch firefox and go to 
http://blog.bigstep.com/big-data-performance/docker-best-practices/

2. After the page is loaded press alt+shift+h.

3. Press tab three times and observe that orca presents the cancel 
button, the jump to button and the heading, as expected.

4. Now press shift+tab and observe that orca presentes an extra column 
before the jump to button.

This happens with orca from master and orca 3.16.2.
Thanks.

--
José Vilmar Estácio de Souza