Alt-F4 doesn’t work on all the metro apps, and you not alway have a trackpad, a mouse or a keybord. So you want to close an app, it’s quite simple: scroll from the toop of the screen to the bottom, and it will close the app you’ve done that on.
So, you have a computer or a tablet with windows 8 and you want to use IE in immersion mode, but it keep launching the desktop version. Don’t rage, it’s a feature. If IE is not your default browser then the immersion mode will not be available. To get it back, you’ll need to set IE as the default browser again.
Go to Internet options (configuration panel) and select IE as default browser again: