I don't think anything has changed there. You either install immediately or you download then install the hard way. Clicking on links will take you to a website. Thunderbird likes to open websites itself, but makes a poor job of rendering the page, and since it doesn't support scripts, many buttons won't work. At this point, I right-click and select "open in browser" to get a fully functioning webpage.

"Download for Windows" simply implies that it thinks you're using Windows, where in the very few cases where this matters, it can offer you the correct version of the add-on. To my knowledge, Enigmail and Lightning are the two best known candidates for this. Since I use a different system, I would see "Download for Linux". ;-)

When you visit a webpage for a Thunderbird extension or add-on, you need to right-click, use "Save As" or "Save Link As", download the file (usually with an xpi extension) then install it. Otherwise it will install in your browser, if you use Firefox, or your OS will complain it doesn't know what to do with an .xpi file.

http://chrisramsden.vfast.co.uk/3_How_to_install_Add-ons_in_Thunderbird.html

Hi,

Sorry for the misunderstanding. What I actually meant was the Thunderbird builtin page (Tools (Alt + T) > Add-ons > Get Add-ons). Please see the attached images.

I checked with an older Thunderbird version (24.2.0). In this case the button is "Add to Thunderbird", and I'm able to directly install the extension after the usual "Software Installation" prompt (and the timer) is displayed.

You're looking at a web page.

Try just clicking on the Install button in the search results list, as shown in my website article.

http://www.chrisramsden.vfast.co.uk/3_How_to_install_Add-ons_in_Thunderbird.html

Just click on Search, at the left, to return to the search results list.