Setting mail.compose.wrap_to_window_width to true should be enough. I wonder why it's not working for you. Do you have any extensions installed?

Thunderbird Version 24.2.0. I culled newer versions because I would have to update Lightning. BTW: I do have a userChrome.css but there is nothing in it that deals with the composer pane.

Extenstions:

Account Colors 9.1

CompactHeader 2.0.9

DOM Inspector 2.0.16.1-signed

Lightning 2.6b2

Signature Switch 1.6.14

The only one that I had in question was Account Colors but it does not have anything in it that should deal with the margin.

You can only set margins in HTML and the wraplength you refer to is for plaintext only. Thunderbird doesn't know about page sizes so it doesn't really make sense to refer to a right hand margin.

What's the logic behind setting wraplength to zero? It's more usually 80 characters or thereabouts. To what does the "The current width is 107 characters" refer?

Perhaps a screenshot showing this supposed "margin" would help illustrate what is worrying you.

With plaintext, properly you either set a fixed width or you set it to flow to fit the available space (and it will dynamically re-wrap if you adjust the window width). Fixed width is problematic in that it may appear OK to you, but may not suit another reader's requirements. And it becomes messy when quoted and re-wrapped.

And then there is the perverse practice of hitting return at the end of each line, which is just another form of user-set fixed width. Of course there is the same problem when this text is quoted in replies.

I have "Compose message in HTML format" checked.

The logic behind wraplength = zero is the TB ignores the setting and should allow the text to wrap at the width of the window. The 107 I should not have entered, it was the amount of text in the current window width and that is relative to my display size.

Nothing is worrying me, it is that I am not use to seeing any program doing this and it is irritating.

See screen shot and there is no hard returns.

So that's just m and space repeated?

I have

mail.compose.wrap_to_window_width;true

…though I have trouble imagining what it should do if not set to wrap to window width. Presumably continue indefinitely off to the right? (which yours patently is not doing.)

Wraplength does not, AFAIK, apply to HTML formatted text. I haven't encountered your argument for zero to disable it before. Mine is set to 72 and has no effect whatsoever on HTML messages.

I have just unset the "wrap to window width" setting and it continues to behave as before. Wraps dynamically to fit to the window. So the real function of this setting eludes me. ;-)

Does yours self-adjust if you do the same? Is it wrapping to a phantom window width value? Or are the lines truly fixed length as they appear?

Is it possible that you're inadvertently using a template that defines a right hand margin?

No template. As you said "wrap to window width" has no effect and this is the problem. I was hoping that there may be two setting that were overlapping and causing the issue, but if it is, no one seems to have the answer. BTW: I get the same effect if in TEXT mode as in HTML.

mail.compose.wrap_to_window_width enables flowed text in plain text emails. Just as mailnews.wraplength wraps text in plain text emails at the length defined.

So neither of these settings are used in HTML email.

Restart Thunderbird with add-ons disabled (Thunderbird Safe Mode). On the Help menu, click on "Restart with Add-ons Disabled". If Thunderbird works like normal, there is an Add-on or Theme interfering with normal operations. You will need to re-enable add-ons one at a time until you locate the offender.

If you send me an email exhibiting this effect, at xenos at gmx dot co dot uk I would be interested to see if it displays properly here. Then we can tell if it is markup doing it, or some wierdness in your own configuration.

Restarting in safe mode did remove the margin. Now the problem is finding out what the problem is. I manually disabled all addons, reset entries in config and even removed some and the issue is still there.

Just went one step further and deleted the Extensions folder and the Personas folder and the problem is still present. What else does Safe Mode disable?

Restarting with Addons Disabled does not solve the problem. Restarting in Safe Mode does.

Took some doing and here is the answer:

userContent.css contained

body { -moz-transform-origin:left top; width:80%; }

the problem was with "width:80%;"

That makes sense.

How did it get there? ;-)

As we'd expect, given this finding, the test message you sent me displays just fine.

I'm not going to tell you that I did it.............. :-(

rdwray said

I'm not going to tell you that I did it.............. :-(

Then don't... but why? I assume you were trying to fix something else you did not like.

Just kidding...

It was just a case of copying and pasting too much.