Rated 5 out of 5 stars

For me it worked well with this patch:
http://www.gramatec.de/quicktext-09.11.7_patch.zip
Uninstall Quicktext - unpack the zip file - drag the xpi file into the add-ons tab in thunderbird. Works great for me.

This review is for a previous version of the add-on (0.9.11.6).