Make sure you have the 
tab open.
In the 'Program structure' panel, select the page you wish to preview.
Click the 
button located at the bottom of the screen.
To close the preview, click the 
button.
Make sure you have the tab open.
In the 'Program structure' panel, select the page you wish to preview.
Click the button located at the bottom of the screen.
To close the preview, click the button.