(Note: While I'm not entirely sure if this be better asked on SuperUser, I guess the fact that you probably will have to mess around in the xpi/jar file with the css settings, should make it suitab...

I have been using Thunderbird for many years now and now I am interested in developing some of my own extensions. I looked over the documentation on their official website but found little support ...

I'm working on a Thunderbird extension, and, unfortunately, can't sort out what's still valid from what's not. There's lots of stuff online, but, most of it is no longer applicable to recent Thunde...

I want to develop a Thunderbird 12 addon. I have written a simple JS function. (File: "chrome\content\myApp.js"). This file is called by a xul-'onclick'-event. I have packed my addon as a .xpi file...

I'm trying to modify a message before it is displayed in the main window in Thunderbird. I can't seem to find 1) An event that will be triggered when a new message is opened/viewed 2) A way to modi...