It appears that even when an iframe has it's background specified as transparent, it's background is white. This means that it is very difficult to have proper looking statusbar widgets within Jetpack -- they always look out of place, and when you defocus the window, they look even worse. Atul mentioned that this was a potential platform problem.

This is indeed a potential platform problem. Specifically, it's bug 235877, which is in turn dependent on bug 130078, the same longstanding content iframe bug that is also a nemesis of dynamic personas (bug 486028). Fixed by changeset http://hg.mozilla.org/labs/jetpack/rev/dea33f66fac4 and followup http://hg.mozilla.org/labs/jetpack/rev/32a8a33e1c8c. Two caveats: 1. This addresses statusbarpanel appearance on Mac OS X only; appearance on Windows and Linux is horked in other ways, so bug 494368 should remain open pending resolution of the issues on those other OSes. 2. This doesn't fix statusbarpanel appearance with Personas installed. At the moment, I don't see a good fix for for the second caveat. Bug 494368, attachment 379121 [details] [diff] [review] tries to address the problem by applying the Personas bottom image to the statusbarpanel backgrounds, but the image only blends into the enclosing statusbar background for horizontally consistent personas (those whose appearance doesn't vary across the length of the statusbar). Horizontally inconsistent images suffer from the wallpaper hanging problem. A real solution to this problem will probably have to wait for the underlying platform fix.

Given that the "fix" is really a partial workaround until the platform bug is fixed, we should indicate that in some way. For now, I'll do so by reopening this bug and making it depend on bug 130078. But if you think it would be better to track the real fix in a separate bug, then reresolve this one, undepend it from bug 130078, and then file a new bug that depends on bug 130078.

Credit where credit is due: the workaround was partly inspired by the following Stack Overflow answer: http://stackoverflow.com/questions/935933/how-do-i-style-a-jetpack-status-bar-panel-correctly

Myk, you mentioned something about this only affecting OS X?

Aza: actually, it affects all three OSes. However, this bug was filed specifically on Mac OS X, so that's where I initially worked around the problem. Yesterday I also worked around the problem in Windows with changeset http://hg.mozilla.org/labs/jetpack/rev/7afbdc39f38b. I haven't tackled Linux yet.

I've now worked around the problem better on Linux by embedding the iframe in a XUL statusbarpanel element. As a side effect, this improves appearance on Windows as well. The workaround is in changeset http://hg.mozilla.org/labs/jetpack/rev/adf12d7ee9a0. I think this is about as good as we can get it on all three platforms until the underlying Gecko bug is fixed.

Woot! Perhaps this is something we should recommend to Ragavan re: the labs wish list for the platform?

Yup, I have already done so (and also the bug on which it depends).

Thanks, Myk!