I found this comment because I too found the current zooming mechanism to be not very effective. I think it would be much more effective to have fine control of zooming using the mouse wheel. I tried both Chrome and Edge browsers, and for both of these the mouse wheel causes the pedigree to scroll up or down. It is easy to move things up and down by clicking and dragging on the screen, so I would much rather have the mouse wheel do zooming. Zooming with the mouse wheel is also more in line with the behavior of other web pages that show images, and what I have naturally come to expect in those kinds of interfaces.