Theme Font & Size Changer
This page contains details for Mac OS X Zoom bug.
While we try to provide a consistent cross platform user interface and implementation for our users, application and operating system level issues may prevent some features to work as expected. Currently, Zoom feature for Mac OS X enlarges user interface elements such as fonts, buttons and toolbars correctly but meanwhile context menus and panels are cut off at the bottom which makes some elements not being accessible for the user. We decided to provide a warning about the issue for Mac OS X users whom to use Zoom feature of Theme Font & Size Changer before they activate the feature.
Please note that this issue does not affect Windows and Linux users. If left default, which 1.0 state, this issue does not affect Mac OS X users, too. Mac OS X users may want to consider disabling the Zoom feature by bringing the value to 1.0 before they need to access hidden context menu and panel elements and re-enabling the Zoom feature after they are done. Or you may want to achieve a Zoom effect by using the Size and Font sections of Theme Font & Size Changer.
Again we should note that the issue is not related to our add-on but to the internals of Firefox and Thunderbird applications. We already submitted bug report of the issue for Mozilla and you may find the details at below link. You may also want to register the Bugzilla and add your comment for the bug to let Mozilla engineers know how important the Zoom feature is for you to be fixed.
Update 5/13/2016 :: Thanks to Mozilla and bug reporters, the bug is resolved and feature is currently available for Nightly versions of Firefox and will hit final versions in a few months. If you rely on Zoom feature for Firefox on Mac OS X or want to try Zoom feature before it hits final version, you may want to download and install Firefox 49 version.
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