I believe the patch on Bug 833511 introduced behavior that is surprising from a UX perspective. I'm running FFx23 on Mac OS X, although I suspect this reproduces on other versions. (1) Adjust your browser window so that it is wider than it is tall. (2) Navigate to a very large, landscape portrait (e.g. http://farm3.staticflickr.com/2833/9407749984_e572f3cbfb_o.jpg). (3) Use the "two-finger twist" gesture to rotate the picture 90 degrees. (4) Note that the image's *height* is now scaled to match the browser's *width*, and bleeds off the top and bottom of the window. A scrollbar appears that allows viewing of the bottom of the image, but not the top.
You need to log in before you can comment on or make changes to this bug.