The small bug is in the login screen. If I type the right password and then I delete it(without do the log in) and I leave the Client opened, someone can login to my account just pointing the mouse to the password section and pressing CTRL+Z. The same thing happens with the username. It is not a big problem if none can access to my computer in that moment, but maybe in a lan party it could be.
For example: I typed the right password and username in a lan party, but I cancelled the login queue( I didnt want to leave the computer with my account logged) because I had to go to the bathroom and I didnt want to give the possibility to someone to log in with my accout leaving the username and the password, so I cancelled them and I left the Client opened(thinking that none could log in with my account). In that situation someone just pressing two times CTRL+Z could log in to my account.
It is just a small account security bug and it need the perfect situation to be used. If you are in a lan party and you have to go away for few minutes, just close the Client(also if he will open the client, CTRL+Z will not work, it works only if you leave the Client opened after that you typed and deleted the username/password).
p.s sorry for my english.