Cheaper but it can fail on slow hardware where the originl panel xbl is applied asynchronously, so that the anonymous content will not be available. That's why you had to add the `if (node)`. It works thanks to the second call make to attach done in `show`.
Can we keep to original code that is known to work and eventually improve this in a followup?
We can easily fix that without any such workaround by patching the original firefox css file.
And now that we have the exact same release schedule than firefox it doesn't change anything patching firefox than the sdk.