User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.0.14) Gecko/2009090216 Ubuntu/8.10 (intrepid) Firefox/3.0.14 Build Identifier: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.0.14) Gecko/2009090216 Ubuntu/8.10 (intrepid) Firefox/3.0.14 When using the zoom feature by pressing Ctrl and turning the mouse wheel, turning the mouse wheel 'down' to enlarge the page size towards the bottom does the exact opposite, i.e. the page becomes smaller. This is unintuitive. The same applies to turning the mouse wheel 'up' to shrink the page into the top corner. Here, the page becomes larger. The behaviour should be changed to shrink the page when scrolling up and enlarge the page when scrolling down. Reproducible: Always

See bug 404775 comment 1. If you don't like it then go to Firefox’s about:config settings page (type about:config into the location bar) and find the “mousewheel.withcontrolkey.numlines” setting, and change it from positive one to negative one. That is, after the change, the relevant pref should be: mousewheel.withcontrolkey.numlines = -1