I have the preference you are referring to (Geary > Preferences > "Automatically select next message") disabled. That by itself does not work for me and is not what I am after.
In Thunderbird the comparable setting is "Automatically mark messages as read" which can be enabled or disabled. When enabled it allows further selection "Immediately on display" OR "after displaying for X seconds".
In Outlook the comparable setting is "Mark mails as read" with three (3) options to chose from: "When viewed in the reading pane for these seconds: X" or "When selection changes" or "Only when opened in a separate window"
What I could envision is to toggle between "Mark as read immediately" meaning marking it as read when the conversation is loaded, which is the current behavior and should be the default. The other option for the toggle is to mark it as read only when any of the following actions on that message is taken: Reply, Reply All, Forward, Archive or Delete (marking it read when deleting is debatable, I would be ok either way). Any other action like move to folder or apply label also should not mark it as read automatically. I have no good umbrella term that I can think of what to call that option though.
Obviously, leave the current function in the message menu to mark the message as read manually in place as is today.
Regarding the outline in https://bugzilla.gnome.org/show_bug.cgi?id=795187: I prefer not to guess when a message or messages in a conversation is marked as read (combination of how much of it is displayed and a time factor if I understand the proposed approach correctly). I would prefer an unambiguous setting that makes it very clear when the marking as read happens. The time factor, meaning setting after how many seconds a message is marked as read, is not interesting for me personally to chose, it maybe for others. But how long I spent looking at something depends on so many factors that setting one value for all messages and all circumstances including external distraction while reading a message that may disrupt that process is in my opinion not needed.
Well, now to the why I don't want messages marked as read: The way I work my emails is based on an approach outlined by Eric Schmidt in the book How Google Works. Here are a few aspects of it:
read enough of it to realize you don’t need to read it = delete OR
read it and act on it right away (and then file it outside of your Inbox) OR
read it and act on it later = file it under Action outside your Inbox OR
read (enough of) it and read more later = file it under Later outside your Inbox.
Additionally it talks about how to handle messages you sent that you have a need to follow up on:
When you send a message with an action item to someone that you want to track, copy yourself and file the message that you sent to yourself under Follow-Up.
Based on this I have a Zero Inbox. I work with three folders/labels only: Action, Later and Followup. Leaving messages as unread will show me the number of messages next to the folder when I move messages to said folders. I like to see that number there at a glance. Once I in fact reply to a message or forward it, etc. marking it as read should occur.
Hope that helps in the design and describes why I would like the option of disabling messages being marked automatically as read.
Axel
