The Preview mode shows how a document will look when you print it.
To toggle the Preview mode, click the toolbar button, or choose the File | Preview menu command, or press Ctrl+F2.
The Preview mode is most helpful before putting the finishing touches to a document and sending it to the printer, just when you wish to evaluate that document as a whole.
You could specify which toolbars and which components of the document window (ruler, scrollbars, document bar, status bar, etc) should be visible when the Preview mode is on (use the View menu).
Even when the Preview mode is on, you have the option to edit the active document (type, delete, copy, paste, format text), but also to open, activate, create other documents. In other words the Preview mode allows you to use any function already available in the normal viewing mode.
A special mode of the mouse - the Magnifying Glass mode - is available in the Preview mode.
Click the toolbar button to activate this mouse mode.
The Magnifying Glass mode allows you to quickly zoom in or out on any desired fragment of your document.
By default, single left / right clicks in the Magnifying Glass mode allow you to zoom in / out by 25%.
Holding the Ctrl key down will switch zooming to 10%.
Holding the Shift key down will switch zooming to 100%.