I would like to operate Firefox by Menus.
Because, from the point of view of cognitive science, I beleive keyboard operation is faster than mouse operation.
Therefor I create this addon to perform search selected text from Edit menu.
You can create your own customized search engine(plugin) by Creating OpenSearch plugins and store it into your "searchplugins" folder.
Mozilla Developer Network - "Creating OpenSearch plugins for Firefox"
Important Information: 2016/03/16
Mozilla is changing a lot of things about add-on development again. So this addon might be stop working in the future.
"The Future of Developing Firefox Add-ons | Mozilla Add-ons Blog"
"Add-ons/developer/communication - MozillaWiki - Upcoming Changes in Add-on Development"https://wiki.mozilla.org/Add-ons/developer/communication#Upcoming_Changes_in_Add-on_Development