I've realized this script didn't work when quoting from '
Show the last posts of this person' or when quoting a
PM.
The script has been updated to
version 1.1 to fix this.
If you prefer not to use it on personal messages, just remove this line:
// @include https://bitcointalk.org/index.php?action=pm;sa=send;f=inbox;pmsg=*;quote;u=*
(However it's completely safe as of course everything happens on your own browser. I'd appreciate if someone can audit the code)