Display the Preview pane by clicking on a test and choosing the
View > Preview menu command, or the [Preview] mode button. The
following describes the Preview pane for the Web (HTTP) service; other
services are a little different, if they support previews.
This pane is useful to get a quick overview of the site, including images. It displays exactly as it would in a web browser, thanks to the Safari web engine. It also includes the HTML source in the upper text area for comparison when hunting for text to look for with the Filters feature. If any filters are used, the output from each of them can also be displayed.
The headers usually include information about the server, a result code, a modification date, or other information. The exact information provided is determined by the remote server.