How about adding a config option? 
Ideally, it might be nice to have this option "per record" or "per logbook", but "per instance" should be good enough.

I'm sorry for being annoying... 
but I have tried to wrap the <pre> tag in a <div> and it seems to do the trick
(the text is a single line with repeating aaa-b-cc sequence)

In the READ mode, the width is limited by the div's width 
(see the first attachment)

In the EDIT mode, the width is only limited by the textarea width
(see the second attachment)

All this is with "wrap=hard" removed. 

Ok, I added an option

Hard wrap = 0 | 1

with the default being "1", so same behaviour as before. If you set this now to zero, you turn it off.

Now waiting for the first people complaining about the very long lines not being readable...

Best,
Stefan

That's great! Thank you very much. 

Didn't work for me. The text is just truncated after the width and no extra lines are added.

Sorry, I forgot to mention that I also added some styles to the <pre> tag:
style="white-space: normal"
(see the screenshot on my previous post)

> Sorry, I forgot to mention that I also added some styles to the <pre> tag:
> style="white-space: normal"
> (see the screenshot on my previous post)

Actually the

style="white-space: normal"

makes the difference, the <div> is not necessary at all!

But I'm not sure that "white-space: normal" is what we want. All manual line breaks in an entry are collapsed and you get just one text block without any new line. See here

https://developer.mozilla.org/en-US/docs/Web/CSS/white-space

I guess we want "white-space: pre-wrap" which keeps the old line breaks.

You can try that out by changing elog.css:

--- a/themes/default/elog.css
+++ b/themes/default/elog.css
@@ -475,6 +475,7 @@ td {

 .messagepre {
   font-family:'lucida console',courier,monospace;
+  white-space:pre-wrap;
 }

and see the effect. If you like it, just keep it. No need to recompile elogd.cxx.

Stefan

> I guess we want "white-space: pre-wrap" which keeps the old line breaks.

Yep. You're right. Thanks!