That would be Closed lid. For WLMessenger you would simply set the "show me as busy" option to the after 5 minutes or 10 minutes and it will show that when the time is up. Or you can simply set to show busy before you step away.
If your laptop has a switch in the lid to put it to sleep as soon as the lid is closed everything will still continue to do just that.
On many laptops you can close the lid and still have your active desktop and other things remain active until the power plan kicks in for sleep, hibernate, turn display and hard drives off, etc. You want it that way when running off of battery to preserve the charge.
If the slide button to unlock and bring up the screen is all it is and you run an ac adapter constantly you can create a custom power plan for high performance where the drives as well as display never turn off or let's say don't for 1hr. or 2hrs. or even longer and simply walk away and return before the time setting.