[trojita] marking a message read when selected

[David Lang]

I thought that if the message window isn't being displayed, selecting a message 
no longer marked it as read.

But in version v0.3.93-15-g2be0e57 I selected wide view, and extended the 
message index all the way to the right (so the mail preview window disappeared), 
but I find that whatever message is highlighted in the index is still getting 
marked as read.

could this please be changed?

David Lang