Switching between tabs after editing a field on IE causes the "Are you sure you want to navigate away" popup dialog box to appear every time

Steps to reproduce on IE:

1. Set up JIRA to have multiple tabs on the edit screen
2. Edit an issue
3. Change the value of a field, switch tabs

This does not happen using Firefox. The dialog should not be shown as the user isn't technically navigating away from the page - the link that they click on the tab invokes javascript:showTab(), which just controls which DIV is visible, so the dirty form data is still kept. I'm guessing that maybe Internet Explorer interprets this as navigating away since the javascript is in the href and not in an onclick event.