The scroll wheel currently zooms in on the sample under the mouse. When zooming in on a particular event, like a packet, if the packet isn't perfectly centered under the mouse cursor, it will quickly slide away from the cursor and off the screen when zooming in large amounts.
Instead, when zooming in, the software should check to see if there is an event very close to the mouse cursor (i.e. 2 pixels away or closer). If so, the software should zoom in on this event instead of the exact mouse cursor location, so it doesn't end up panning off the screen.