New: LibreWolf (Dec 03, 2022), Platform 22.0.1 (Jul 21, 2022)
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and audio is unintelligible
We don't alter SeaMonkey to make it portable, we just have something help it start the right way and clean up when it exits. Also, you've included no details about what page has this issue, what OS you are on, etc. I just tried SeaMonkey Portable 2.11 with the captcha on PortableApps.com's account signup page and it worked as expected. Captcha was visible and audio sounded as it is supposed to (which, incidentally, is nearly impossible to figure out).
Bug closed 2012-08-22 after no response from reporter
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