Shut down Metro apps
Run a Metro app, and you'll notice one thing is missing --- there's no apparent way to close it down. Usually, this isn't a problem, just let it run in the background. But there are times when an open Metro app may drive you off the deep end. For example the Zero Gravity app has a soundtrack designed to set your teeth on edge. Switch out of the app, and the soundtrack still plays.
There's a simple if kludgy workaround. Get back to the main Metro interface, then click the Desktop tile. That will switch you to the Desktop, and the music stops immediately. The app will still run for a minute or so, but the sound will be off. But after a short while, the app itself will shut down.
Get to the oldstyle Windows Control Panel
What happened to the Windows Control Panel in Windows 8? It seems to have vanished. The Start button on the Desktop no longer launches a menu including the Control Panel. True, there's a Metro Control Panel app, but that doesn't include all the fine-grained controls and features of the oldstyle Control Panel, and it also doesn't let you change the Desktop.
You can get to the oldstyle Control Panel relatively easily, though. In the Metro interface, click Control Panel, scroll to the bottom of the screen and click More settings, and you'll be sent to the Desktop's Control Panel, in all of its oldstyle glory.
Fast app switching between Metro and Desktop apps
There are several quick ways to switch between open apps, even if they're a mix of Metro apps and Desktop apps. Pressing Windows Key-Tab does the trick. But if you'd like to switch among apps without using the keyboard, you can do that as well. Move your mouse pointer to the far left of the screen, and a small icon appears of the last app you were running. Click it and you switch.
Metro screen capture
Want to capture a screen from Metro or one of its apps? If you try a Windows Desktop screen capture program, it may not work --- press the hot key for screen capture and nothing may seem to happen. Here's a workaround. Press the hot key, then get to the Metro desktop and click Desktop. At that point, you'll be sent back to the Metro screen you wanted to capture, and your screen capture program will spring into action --- at least, that's what happens to me using Snag-It. Your experience may differ.
There's an even more awkward way. When you're inside a Metro app, put your mouse pointer at the bottom left of the screen and then click the Share button. You'll then be prompted to share a screen capture using Metro's Socialite app for Facebook. This technique won't work on the main Metro interface itself, and may not work for every app.