trouble getting links in emails in thunderbird to open with palemoon

[oldwierdal]

Hi!
I just installed Pale Moon 27.6.0 using pminstaller. It was embarassingly easy. The tutorial on importing stuff from firefox to palemoon was right on.... again, so easy it was boring! But, when it came to trying to get links in thunderbird emails to open with palemoon, well, not so easy.
The first launch of palemoon opens with "do you want to make palemoon your default browser?" 'Yes' Unchecked the box for showing this at every startup of palemoon. Opened Thunderbird, Edit>Preferences>Attachments. Scrolled down to HTML, http, https, to change Action from 'use Firefox' to 'use Pale Moon', and there was no 'Pale Moon' available. So, I opened Start>System>Preferences>Personal>Preferred Applications>Web Browser> And there was no 'Pale Moon' available. I launched palemoon again, and Edit>Preferences>General>System Defaults> And read "Pale Moon is currently your default browser." So, I did what must always be done with MSWin, I rebooted...... no help. Pale Moon launches, and everything works fine. But, again, in Thunderbird, Edit>Preferences>Attachments, I could not change 'use Firefox' in any of them, Pale Moon was not available.
So, I uninstalled Firefox, clicked Start>System>Preferences>Personal>Preferred Applications>Web Browser, and "voila!" There was Pale Moon. I checked preferences again in Thunderbird, and HTML, http, and https all three had Pale Moon available. Everything now works as intended. Actually, maybe it's just me, but it seems like Pale Moon is just a bit quicker. Also, I had been using Classic Theme Restorer with Firefox. No need for that with Pale Moon. The theme right out of the box looks great.
So... the question is, why did I have to un-install Firefox in order to get things to work right?

Thanks,
owa

[Terryphi]

This is how II made Thunderbird open links in Palemoon (in Linux):
In Thunderbird profile folder change references in prefs.js and mimeTypes.rdf from firefox to palemoon. To revert to Firefox just change back. For safety save copies of the original files before you start.

[oldwierdal]

Thanks, but, as I said, Pale Moon was not visible as an option for anything until I un-installed Firefox. By the way, I neglected to mention in my original post, I'm running on Linux Mint 17.3, with Mate' Desktop.
I have a cloned backup of my entire system on a separate hd, and I intended to try to recreate the problem on the clone. However, I have an automatic backup script which runs prior to shut-down. I got sleepy, and went to bed without shutting down the computer. My wife, unaware of the issues I was having, shut the computer down before she went to bed. So, that option is no longer available.
I also have Linux Mint 18.2 installed on a third hd, which I use for testing other systems. If I can get a few hours of uncontested computer time, maybe I'll see how it goes on LM 18. Keep in mind, though, that LM 17 and LM 18 are significantly different, so the results may or may not tell me anything.
All of that said, Pale Moon is installed, and everything works just fine. My congratulations to the wizards who did all the work to fork this from Firefox. Great job!

Thanks again for the response,
owa