Hmm, this will break when there are no graphs (only frames) in the dashboard: `Cannot call method 'getPropertyValue' of null`.

Unfortunately, I introduced two breakages in my previous widget PR which are needed to test this PR here fully. I created a PR to fix these: https://github.com/prometheus/promdash/pull/17

To save you some rebase-conflict work, I have another ephemeral branch which contains the commit from this PR here, but rebased ontop of my changes from PR 17: https://github.com/prometheus/promdash/commit/2ea181d60c35c2c65afe2fdd364eaf649c788cf9 - you'd just need to fetch it into this PR and make sure the author is you again.