Receive Facebook Message, Can someone tell if i read their message?

I know when i receive a message on facebook, and then click on that message logo and then click on the message and read the message, it will be shown as read to the other person. Such as seen at whatever time. However, what happens when you dont actually click on the message but you click at home and then you actually read the message?
For example, i see someone sent me a message and then read it without clicking on the actual message b/c i see the message on the left of it. For the messages, it still shows the 1 as the message that i have for me.

Does this mean that its shown to them my message is seen?

Want to rephrase this. When i get a message, it would have a 1 in the message icon at the message notificiation. I would click on it and then it woudl show the message. Does this mean it will be shown as seen? The thing is in the left side where it shows messages, it still has the 1 there.
However, i assume once i click on the message icon with the 1 message notififciation , that mean it will be shown as seen? I didn’t click on the actual message such as i saw the who send me message and saw the message, and that is all. Their message was short and it wasnt a long one so im curious if its going to be shown that i read their message.

Far as I know only if you click on the actual message - if you click it will be marked read/viewed - but I don’t think it stays visible very long. Just viewing the messages folder shouldn’t do that

I don’t think so either. Even if I have a friend’s message thread up in the little chat window, their new message isn’t marked as read (ie, the red notification doesn’t go away) until I actually click on the chat window. So I think you have to engage with the message itself for it to be read. Preview doesn’t count.

Someone else posted

i have actually wondered this myself at a certain time. i’m assuming it doesnt show as “read” to the sender if you only clicked the notification but not the actual message
So can anyone here confirm this is true then? I guess that is what i did because i only clicked on the notification but not the actual message.

anyone nkow?