jboss.org JIRA server running at https://issues.jboss.org provides streamlined functionality of "Start Progress" action now, which is in align with latest JIRA default workflow.
You had to manually assign issue to yourself to be able to perform "Start Progress" action before this change. Now, the "Start Progress" action is available to all Assignable users (potential developers). Status of the issue is changed and you are made issue's Assignee once you use it, so one less click is necessary and workflow is more user friendly.
Enjoy