Just installed the todoist button on thunderbird 17.0.3 on Linux and the todoist button didnt show up.
Please try to right-click on the toolbar at the top of Thunderbird and see if there's a TD icon that can be added there. If there is - drag & drop it onto the toolbar. If not - try to install Thunderbird 17.0.5 and let me know if the issue persists.
i've got the same problem. And have Tbird 17.0.5. I've opened and restarted Tbird a few times, nothing that shows up the TODOIST button or icon. Help?
Have you right clicked somewhere on the Thunderbird toolbar area (usually beside a tab), and clicked on "customize"? This should give the option to add Todoist.