Joachim Backes wrote:
I'm running F15 with thunderbird-5.0, and I'm having problems
to install
a thunderbird extension file (suffix: xpi) by the TB extension manager:
if trying "tools->add-ons->extensions", there is no button for
installing a xpi file.
On the add-ons page, you have to click on the tool button that is next
to the search box at the top. There is a "Install Add-on From File..."
option.