Re the editor, the Gecko editor component has long been plagued with the issue that the module owner didn't really want to hold that position. For a time, the owner was completely hostile to anything Thunderbird, despite the fact that Thunderbird was the heaviest and most notable implementation of the editor.
I will also point out that there is actually some fairly deep integration code within the Mozilla editor with Thunderbird's compose backend (particularly in regards to the need to generate inline embedded images). There have been attempts to replace the editor with a more functional one in the past, but they all came to naught.
Thanks for that reply. That makes sense. My comments about the editor were deliberately made from the perspective of the end user. Whilst I used hyperbole to emphasize the fact that the editor was the main culprit, I agree things usually are not that simple.
However, the key point I was trying to make still stands which is that irrespective of the state of the underlying code/Gecko editor components etc., etc., for some reason third party developers (here BlueGriffon's developers) have managed to tame the code in a much more successful way than Mozilla itself has done. The implication being that as principal developer Mozilla should have been able to do a better job than third party developers should. Thus, it amply demonstrates Mozilla's lack of commitment to the Thunderbird project per se (and that this has been so for a very long time (ipso facto, so have the bugs/problems) without Mozilla bothering to attend to them).
I am not a Thunderbird add-ons developer/TB code expert so there's little point me attempting it, but it would be very informative to find out why the BG editor works and the TB one is so brain-dead. As I see it, it's important to cut to the core of these problems if for no other reason than to show the skeptics or those who've simple requirements and find little or no problem with TB that there are real longstanding problems with Thunderbird and that some of us are not just being argumentative for the sake of it.
I will also point out that there is actually some fairly deep integration code within the Mozilla editor with Thunderbird's compose backend (particularly in regards to the need to generate inline embedded images). There have been attempts to replace the editor with a more functional one in the past, but they all came to naught.