This subject has been recently covered.
I will leave the work of looking back in the last few months for it, to you. You might spot some othe good stuff while you browse.
Thanks for your prompt answer, though I seriously could do without the snippy "You might spot some othe good stuff while you browse." I spent about a half hour searching through the forum, and through the user guide, prior to posting. I didn't find anything relevant. Mea culpa. But I certainly did make an effort.
I guess you must mean thread 198807 "Sigil 0.6.2 for Mac repeatedly crashes on starting". Am I right?
What follows probably sounds like complaints, but should instead be taken as observations. I wouldn't normally bother to make points like this, but since your snippy comment seems to imply laziness on my part, well, here they are.
After hunting around some more I found the wiki page "InstallationInstructions", which indicates OSX 10.8+ is required. Before posting, I'd tried to discover whether there was an OS requirement, and looked at the sigil user guide. Finding a "installation" section there which didn't mention any such requirement, I failed to realize there'd be additional installation information in the wiki. Actually, I failed to realize there even was a wiki, since the users guide has the appearance of being thorough.
Prior to that, I looked for release notes for Sigil-6.0.2, hoping (actually expecting) that these would indicate any hardware and/or OS requirements. I didn't find any such release notes (hunting around code.google.com/p/sigil). Maybe they are there, somewhere, but I didn't find them. Many programs include such installation information in a file as part of the download. It doesn't look like sigil does that. From what I call tell, release notes are posted to this forum when the release is made. E.g. thread 198756. Except a quick glance at 198756 (as I did take prior to posting) leads one to think there are no special requirements. One has to read down a ways before one discovers someone had problems running it with the same OS I am (though, even looking at that now, I don't think I would have recognized the crash log posted there as being related to my problem).
In summary, I do thank you for your reply, which I believe has answered my question.