Here’s a nifty trick for getting a file preview in Windows 7. Select an image or document in File Explorer and press the Alt + P keys.

Now you’ll get a preview pane for the file.

The pane will remain turned on until you press Alt + P again to turn it off.
~ Cynthia
Works in Windows 10 too.
That’s a capital P, so the keystroke combo really needs to be Alt + Shift + P. Doesn’t work with Alt + p