When zooming by holding "ctrl" and rolling the mouse wheel, the most intuitive thing would be for the zoom center (that is, the point that does not move while zooming) to be located where the mouse cursor is currently pointing. However, this is not the case.
*** Bug 68875 has been marked as a duplicate of this bug. ***
*** Bug 89547 has been marked as a duplicate of this bug. ***
This is fixed in 4.3.3 and 4.4 by Caolan in bug 83588.