One of the most requested features after we released Firefox on Maemo (Fennec) 1.0 was for a way to "free-form" zoom. Fennec already supported what I call a "structured zoom" - that is, double-tapping that zooms to fit the part of page structure (a column of text, an image) that you're tapping on. That method doesn't help you in every circumstance, though, and that's where a free-form or arbitrary zoom mechanism is useful.
Devices that support multitouch almost all now use the pinch-to-zoom gesture for this, and that's what Fennec will do on such devices as well. The Nokia N900, though, is single touch only, so for version 1.1, Fennec makes use of the device's rocker button to allow free-form zooming in and out:


Two interesting things!
Ideally, you won't notice either of these things in day-to-day use; it should just feel like it works the way you'd expect.
Posted by madhava at May 13, 2010 04:35 PM