This extension adds buttons to Enlarge/Reduce the Font Size (Not Zoom) on the Toolbar.
Current Version is here.
https://addons.mozilla.org/en-US/firefox/addon/9872
and x2 ()
var FontSize_Extension = { enlarge: function() { if( ZoomManager.useFullZoom ) { ZoomManager.useFullZoom = false; FullZoom.enlarge(); ZoomManager.useFullZoom = true; } else { FullZoom.enlarge(); } }, enlarge2: function() { if( ZoomManager.useFullZoom ) { ZoomManager.useFullZoom = false; FullZoom.enlarge(); FullZoom.enlarge(); FullZoom.enlarge(); FullZoom.enlarge(); FullZoom.enlarge(); FullZoom.enlarge(); ZoomManager.useFullZoom = true; } else { FullZoom.enlarge(); FullZoom.enlarge(); FullZoom.enlarge(); FullZoom.enlarge(); FullZoom.enlarge(); FullZoom.enlarge(); } }, reduce: function() { if( ZoomManager.useFullZoom ) { ZoomManager.useFullZoom = false; FullZoom.reduce(); ZoomManager.useFullZoom = true; } else { FullZoom.reduce(); } }, reset: function() { FullZoom.reset(); } }