K9 beta - Envelop symbol

In the beta version there is an envelop symbol to mark messages as read/unread.
I assume that it’s meant to be closed for unread messages and open for read messages. But it’s the other way around.
Is it by purpose, maybe telling me what the outcome will be after klicking? I would find it more intuitive to show the present status but I could understand the other logic, too…

The items in the toolbar are actions, not status indicators. When you click the closed envelope the message will be marked as unread. You can also long-press the icon to see the name of the action.

Yes, thanks. I already found out about the short and the long press effects.
But the icon is not only an action, it’s a status indicators, too - as it changes its status when you do the action.
And the status indicator part is what is counter-intuitive for me, personally. So, I wanted to asked if it is meant this way or the other way around…