In addition to the normal Status value for all JIRA issues (and the associated workflow), JIRA-Agile epics have an additional field, the Epic Status.
This field is generally well hidden in JIRA issue displays and edit dialogs, but it can be brought to light in an issue filter (see the EpicStatusFilter.png attachment).
The Epic Status can pretty much only be changed, as far as I can see, by using the pop-up menu for epics in a JIRA-Agile board's Plan view (see the EpicMenu.png attachment for the "Mark as Done" action).
The latter is the only way that I can see to get an epic to disappear from the Plan view, and it is apparently completely unrelated to the ordinary Status. This is pretty counter-intuitive.
The request here is to either, ideally, link the two so that either way of marking an epic as Done updates both status values, or at least to facilitate the display of the Epic Status in the normal display of epics as issues.