I tried changing the global setting for horizontal scroll to 'zoom in/out'. Because I also have a defined shortcut of double-clicking CTRL to invoke the Wizkey utility (antibody-software.com), the Wizkey dialog keeps popping up in different places on the screen as my font size increases and decreases. Most distracting, but I am not sure what you can do about it! Essentially you need to emulate HOLDING control down, then using mousewheel, not pressing control repeatedly to zoom.