Steps to reproduce:

1. add a graph to a dashboard, add an item that has at least one simple trigger associated with it, make the trigger limit visible on the graph, apply and save.
2. hover your cursor rapidly over the trigger line(s) and the closest graph widget edge.

Result:
the area where the simple trigger annotation is shown on cursor hover gets progressively more and more haunted by annotation frames past.
Expected:
the dashboard should remain ghost-free.

the frames are persistent and only seems to go away on a page refresh.