[Evolution] Query about editing quoted text in Plain Text mode

[Milan Crha <mcrha redhat com>]

        Hello,
for the background: WebKitGTK+ deprecated C DOM API few releases back,
thus I'm slowly changing the code to use JavaScript Core API instead.
The preview panel is done for the upcoming 3.36.0 and I'm slowly
fighting with the editor part. There will be some functionality dropped
and some (I hope good) added. I'd like to depend on WebKitGTK+'s
functionality as much as possible, which has its pros and cons.

My current query is:

Is editing of quoted text in the Plain Text mode used?
What do you expect from it?

Tomas Popela (continued the work started by Dan Vratil) did a great job
in preserving the behavior as close as possible to what users were used
to from times of GtkHTML, where editing text in quotation kept the
quote character ('>') at the beginning of the line when the paragraph
text had been changing. That's fairly complex code to maintain, thus
I'm thinking of dropping it, instead of rewriting it in JavaScript.
Without it the quote characters would be there, but they will be like
any other text, possible to edit/remove and so on. They would be
switched to 'blockquote' when changing format to HTML and back to quote
character on change to Plain Text mode.

I checked some other GUI editors what they do with quoted text in the
Plain Text mode and this is what I found:

 * Thunderbird (68.4.1) - does nothing when editing it, only
   re-wrapping function can fix/add quote character;
 * SeaMonkey (2.49.5) - works pretty much the same as Thunderbird;
 * KMail (5.11.3) - does nothing when editing; has in Edit menu
   "Add/Remove Quote Character";
 * Claws Mail (3.17.4) - keeps quoted text quoted while typing new text
   (when long lines are wrapped), but not when deleting quoted text.

That is, none of the above work any similarly as the current Evolution
in this regard.

I do edit quoted text myself, mostly to correct wrapping and to split
the quoted text into parts, under which I write my comments. While I'm
used to manually wrap the text (using Delete/Backspace and Enter keys),
it doesn't scale for long text. Having the Format->Wrap Lines extended
to preserve quote character appropriately on re-wrap, I'd probably get
use to it sooner or later. I sometimes create my own quoted part just
by adding the quote character at the beginning of the line.

I guess dropping "quote paragraph lines while typing in Plain Text
mode" functionality would not cause any significant harm long term
(habit factor considered), especially when its drop would simplify the
code and other functions a lot (including undo/redo), but I thought
I'll ask for an opinion here too.

        Bye,
        Milan