I was having strange issues where top would be a staticly defined value, and if the y axis of the draggable is resized, the tooltip stayed where it was and didn't move with it.

I could be wrong about this as the number of iterations i went through at that pont and area was large, so likely it is fragmented and worth trying again.

Does it make sense to you that the top would be static? It was not number of pixels between the bottom of the container and the top of the event.