Shortcut: Shift+F4
Opens a new view on the current file in a new window.
A new view will operate on the same underlying file, any changes will be reflected immediately in all other open views. Each file view window can have it's independent mode or settings.
Multiple views of the same file are indicated in the window title with a count after the filename:
[filename:2]
Only closing the last view for a file, will actually close the underlying file.
See also: File|Exit Window|Windows