First of all, i'd like to say the taskboard is perfrect. The operations are definitely smooth. It provides a KANBAN like place for the iteration throughout the project team.
But there is a bug of close iteration button status. The scenario is if all the tasks are marked complete, the button disappears. if any one of the tasks is not completed, the button shows and i am able to click it.
The repro is move all the task to completed column, the button still appears.
If you refresh the page it just works fine.