Hmm, WFM in a Build built from http://hg.mozilla.org/tracemonkey/rev/641d4c7e217b on WinXP.
Mhm. Can someone else verify? I deleted my profile and rebuilt but maybe its one of those days. I will try the nightly.
We do have lots of test coverage of the addons manager being opened: http://mxr.mozilla.org/mozilla-central/search?string=about%3Aaddons&find=test
Note that this only happened when I was trying to open the addons manager from about:home. Once I navigated to a different page it did open. I will check with a rm -rf clean build whether this persists.
Please renominate if we can reproduce, but for now this looks like it's WFM.
Can this be resolved?
WFM on the 07/17 Nightly. Removing QAwanted until enough details are available that QA could reproduce the issue.
Can anyone still reproduce this issue or should we just close it?