This a bit annoying. Not a real "bug", but maybe you can do something about it.
As the title says, I switch from Animate mode to Setup quite often, and I rapidly scroll up/down with the mouse wheel on the Hierarchy. But all too often it's the Viewport what zooms in/out instead.
It actually happens in both directions, from Setup to Animate as well. The only way to make sure it doesn't happen is hovering up and down just a bit before trying to mouse-wheel-zoom.
That is: this only happens when I Ctrl+Tab and immediately zoom in/out on the already hovered Hierarchy, without moving the mouse at all.
Maybe an additional check could be done to make sure of what UI area we're actually hovering?
Thanks!