Changes

* install the extension into Thunderbird manually (this needs an explanation as ** It is best to how do this is done - is it by copying the .XPI file into this directory? or using Tools -> Extensions -> Install from within Thunderbird?)* . Then you will notice that can find the additional folder appeared containing your extension in "%PROGRAMFILES%\Mozilla Thunderbird\extensions\" - this .** Alternatively, you can use any unzip program to look inside the XPI file (which is your new just a zip file with the extensionchanged to XPI). However, you will not know which folder the XPI will extract to unless you look inside the install.rdf and look for id.