Good point, thank you. It appears to get calculated for the entire object area, the bubble's peak included. That might make it not only unnecessary complicated but also mislead the user with its vertical alignment text frame setting. In particular "centered" doesn't visually work well this way since the entire object height is respected to calculate the center – whereas me user would expect to get the middle for the ellipse only, never influenced by the lenghts of the 'stinger'. Video: Diff