Hi @rkent!
Thanks for your investigations in QuickText add-on problems. Maybe @s1n88 could provide the code changes and contact you by email to fix the problems and get a fully working add-on again for the upcoming Thunderbird 45.
Which license is used by QuickText Pro source code?
Regards
Alexander Ihrig
Thunderbird Mail DE
QuickText (both community and Pro) have no license, which means de facto the license is "All Rights Reserved".