vchin, so was this a regression which doesn't happen in the current Nightly? Does it happen still on older Nightly? We really need some regression range here, from someone who can reproduce the issue.
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vchin, so was this a regression which doesn't happen in the current Nightly? Does it happen still on older Nightly? We really need some regression range here, from someone who can reproduce the issue. Flipping dom.popup.experimental might help here, but we need to understand why the behavior has changed here. dom.popup.experimental has been disabled all the time.