Kostia, regarding your first question.
User is considered "offline" when he logs out. Sometimes users don't use "log out" button themselves. They can, for example, just close the browser. In such cases system automatically logs the user out if the user has been inactive for 30 minutes.
So it is ok, if some users stay "online" in chat, even though they were active 1 minute ago. Latest activity can go up to 30 minutes with users still showing as "online" in chat.
Regarding your second report:
>>One more issue.. as you can see from my pic..messages exchange their place.. then i push on messages page i can see that somehow thiese messages quick exchange.
I am not sure how I can reproduce this. Can you provide more detailed steps?
Kostia, can you please provide us step-by-step instructions how to reproduce your second issue items switching places - as I can't see anything from the screenshot or your explanation?