Theming capabilities on addons.mozilla.org (AMO) will undergo significant changes in the coming weeks. We will be switching to a new theme technology that will give designers more flexibility to create their themes. It includes support for multiple background images, and styling of toolbars and tabs. We will migrate all existing themes to this new format, and their users should not notice any changes.

As part of this upgrade, we need to remove the theme preview feature on AMO. This feature allowed you to hover over the theme image and see it applied on your browser toolbar. It doesn’t work very reliably because image sizes and network speed can make it slow and unpredictable.

Given that the new themes are potentially more complex, the user experience is likely to worsen. Thus, we decided to drop this in favor of a simpler install and uninstall experience (which is also coming soon). The preview feature will be disabled starting today.

It’s only a matter of weeks before we release the new theme format on AMO. Keep following this blog for that announcement.