From MozillaZine Knowledge Base
Gecko 1.9 implements full-page zooming. Mozilla Firefox exposes this functionality in the user interface through the “View → Zoom” menu and allows zooming by holding down “Ctrl” and pressing + or - or by scrolling the mousewheel up and down.
This preference specifies the maximum amount the user can zoom in a page as a percentage. It was previously named fullZoom.maxPercent.
Possible values and their effects
An integer representing the maximum zoom level as a percentage. Default is 300.
First checked in
2008-02-13 by Reed Loden (patch by Elmar Ludwig)
Has an effect in