Does gmail web interface use IMAP ?

I’ve been writing a gmail client as a demo just to kick around rbcurse’s newer features.
When I fetch the body of a mail, it takes a little time. This also sets the message/mail as READ on the server.

However, on gmail’s web interface, clicking on an unread mail instantly displays the body. This means that gmail has downloaded the body in the background *without* setting off the flag as READ. So is gmail using its own IMAP api, or something else ?

Also, some operations from the gmail gem such as star and unstar don’t seem to work. Could be a bug in the gem, though. However, however a strange thing is that the UID of a starred message in the Inbox is different from its UID in "Starred". So when i am in any folder, i have no way of knowing what the starred messages are. How does Gmail itself manage identifying starred items.

gmail client using rbcurse