Comment 3 for bug 1017247

Just to be clear - what happens here is that the "Cleanest Addon Manager" addon accesses (and hence, causes the initialization of) the stylesheet service from it's startup() bootstrap method.

Our menubar registers a UA stylesheet in its chrome.manifest which is used to set the menubar to display: none and the toolbar to min-height: 0. The stylesheet service registers this UA stylesheet when it starts, but the "Cleanest Addon Manager" causes it to start before extension chrome is registered for non-restartless addons - such as ours.

This isn't the first time something like this has come up (see https://bugzilla.mozilla.org/show_bug.cgi?id=693687, which was also caused by a restartless addon accessing internal services before extension chrome is registered).

There shouldn't be any reason why this problematic addon couldn't access the stylesheet service from an idle event, thus avoiding the issue.

However, as this may not be the only addon doing something like this, I may add a workaround for it in our extension by not relying on chrome registration to register our stylesheet (and doing it manually instead - much in the same way as Cleanest Addon Manager does) :(