Go to the Admin panel for a repository.
Click on "Issue tracker settings"
Under "Components", "Versions", or "Milestones", enter the text for the new element and click the 'add' button.
The 'add' button should now be turned into a spinning graphic and you are unable to enter additional elements without refreshing the webpage. The elements that were added are actually recorded though and DO show up when the webpage is manually refreshed.
Additionally, clicking the remove icon (red button with a minus in it) to remove a component/version/milestone turns the red button into a spinner and doesn't update the webpage unless it is manually refreshed.
As well, the spinning busy icon also replaces the "Set default values for new issues" button when it is clicked.
This bug has been reproduced in Chrome, Safari, and Firefox for Mac, and Chrome and Firefox for Windows.