When you confirm that it is, Chrome tries to open a window and crashes: chrome: segfault at 1 ip 00007f67b86af628 sp 00007ffc2dce47c8 error 6 in libc-2.31. Uninstalling Firefox triggers a prompt (first time you click a link in Skype) asking for confirmation that Google Chrome is indeed the default browser (although it has already been set). Thunderbird is a free, open-source, cross-platform e-mail and news (NNTP) client developed by the Mozilla Foundation. Xdg-open opens the default browser in both cases but the links accessed via the program seek Firefox. As of July 2012, Thunderbird has transitioned to a new governance model, with new features being developed by the broader free software and open source community, and security fixes and improvements handled by Mozilla. First pick the folder for your locale and then download the package. Thunderbird 45 can be downloaded from here. Some other people report the same problem with screenshots (in Japanese). Actual results: The left folder pane does not show up.
THUNDERBIRD MAC OS DOES NOT OPEN CHROME LINKS MAC OS X
Thunderbird 45 will continue to work with Mac OS X 10.6, 10.7 and 10.8 but will not receive any further updates or security fixes. User Agent: Mozilla/5.0 (Macintosh Intel Mac OS X 10.9 rv:31.0) Gecko/20100101 Firefox/31.0 (Beta/Release) Build ID: 20140716183446 Steps to reproduce: OS: Mac OS X Mavericks 10.9.4 Upgrade to Thunderbird 31. If you package the program with strict confinement then it uses the correct browser, however, with -classic it looks for Firefox. Option 2: Download Thunderbird version 45.
In your user Library, right-click the Thunderbird folder. In the Applications folder, right-click Thunderbird.app.
It is built with Electron and the program needs the -browser-support plug to run. Here is the full answer so not to leave the Thunderbird folder in your Library folder: Uninstalling Thunderbird in Mac OS X.
I have come across the same problem when playing with Etcher. This issue is still present with the Skype snap.