As requested in the parent ticket by dobedobedoh's peer review, this subtask was split to focus onto adding a way to "reply with quote" when replying to a post.

Our original idea was:

The mod_forum modification will be needed to provide a "Quote" button besides the "Reply" button in the forum discussion and to paste the quoted post's content into the Atto editor on the following page.[...]

Andrew had concern about this link:

With the reply with quote component, I have a few concerns, namely the fact that you can currently already reply to a forum post. I'm concerned with the prospect of adding an additional action to the post and how that would be presented. A couple of thoughts on potential solutions:

1. we make this a per-user preference
   •  no additional UI component within the forum UI
   •  we have too many such preferences
   •  this doesn't give enough granularity - it's either on or off for a user, and you can't choose it on a per-post option
2. we add a "quote" link or similar which performs the reply + quote action
   •  simple and hopefully clear
   •  UI clutter
3. we incorporate this change into an inline editor change
   •  puts everything into the same place
   •  keeps everything in context
   •  not really part of this request and would still need an option to include the reply but may provide different options for doing so

I don't really have a suggestion for how to solve this, and I think we'd need to see some mockups and ideally to involve the UX team (acorado, barbararamiro).

To illustrate our initial idea, I made a quick mockup based on demo.moodle.net:

It basically just adds this additional button and can be optionally accompanied by nice FA-icons:

<div class="commands">

    <a href="https://demo.moodle.net/mod/forum/discuss.php?d=1#p1"><i class="fa fa-link" aria-hidden="true"></i>

&nbsp;Permalink</a> | 

    <a href="https://demo.moodle.net/mod/forum/post.php?edit=1"><i class="fa fa-pencil-square-o" aria-hidden="true"></i>

&nbsp;Edit</a> | 

    <a href="https://demo.moodle.net/mod/forum/post.php?delete=1"><i class="fa fa-times" aria-hidden="true"></i>

&nbsp;Delete</a> | 

    <a href="https://demo.moodle.net/mod/forum/post.php?reply=1#mformforum"><i class="fa fa-reply" aria-hidden="true"></i>&nbsp;Reply</a> | 

    <a href="https://demo.moodle.net/mod/forum/post.php?reply=1#mformforum"><i class="fa fa-quote-left" aria-hidden="true"></i>&nbsp;Quote</a>

</div>

I still think that this approach would not clutter the forum post interface too much and would be the most straightforward way to add this feature. You will find similar buttons in existing forum solutions. The only real downside I see is that the user has to decide if he wants to quote anything before starting to type his answer.

Regarding Andrew's potential solutions, I would like to give this feedback from my point of view:

• "we make this a per-user preference":
  I agree that this is a bad idea, because it will make the feature effectively unreachable for users who didn't enable the feature.
• "we add a "quote" link or similar which performs the reply + quote action":
  This is the solution which I described above and I think we could argue if this is UI clutter or not.
• "we incorporate this change into an inline editor change":
  I like this idea because it effectively would be the way how commenting systems on Facebook and other platforms work today. The only thing I am afraid of is that we would have to rebuilt more things that we intended to rebuild at first.

brendanheywood also commented this:

Another UX idea to throw into the brew: most good email clients do partial quotes based on the currently selected text. ie if you hit reply it's just normal, but if you selected a sentence or paragraph and then hit reply then you would get the quoted text in your reply. This work fantastically when you want fine grained responses.
You could either treat this as a bonus UI sugar on top of 1,2 or 3 above, OR you could make this the only way to access this feature. But that would mean some people may never discover the feature. To make it more discover-able if you select some text, then the reply button should swap from 'Reply' to 'Reply with quote' and you could also have a quote button along side the select text. Mockup below. One downside is that this would be harder to support on mobile, but doing any sort of extensive commenting is a pain on mobile anyway

I think this is a really nice idea and should definitely be added as a bonus. In our original idea, the user would quote the whole previous post and would have to get rid of all parts which he didn't want to quote manually.

Regarding the access to this "part quote" feature, we would have to spend some more thought as it's all about visibility.
If you want to have a look at part quote in action, have a look at https://github.com/blog/1399-quick-quotes where Github invented this as an invisible feature 4 years ago. On the other hand, Github has not yet a "real" quote button for comments (see https://github.com/dear-github/dear-github/issues/169).

There's one more important this to consider: Edge cases.

In the parent ticket, I started with these basic assumptions:

• We propose to create a solution which leverages the possibility of Moodle's rich-text editor as this will cover the clear majority of Moodle users. A quote feature for users who have disabled the rich-text-editor in the user profile (this includes the Plain Text, Markdown, Moodle Auto-Format formats) would be fundamentally different and is not covered by our project scope at the moment.
• Currently, Moodle ships with two rich-text editors: TinyMCE and Atto. We consider only Atto to be maintained in the long run and thus would like to focus on Atto.

This means that users who have disabled the rich-text-editor in their profile allcompletely or who are still using TinyMCE should not (or rather must not) see the quote button or be able to use the quote feature when answering a post.