There is no explicit support for this in the interactive charts. You can hack around the problem though:
https://groups.google.com/d/msg/google-visualization-api/BPNbQ3GKCdg/R-7P0RwBOq8J Search the group to find more. -- You received this message because you are subscribed to the Google Groups "Google Visualization API" group. To view this discussion on the web visit https://groups.google.com/d/msg/google-visualization-api/-/6S8s1G0RTXYJ. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/google-visualization-api?hl=en.
