Adobe GoLive 6 offers an integrated "split source" display that allows you to view and edit your layout and source code simultaneously.
To reveal the split source, click the show/hide button in the bottom left
corner of the document window. You can also choose View -->Show Split Source (Command/Control-Y) from the menu. Hold the Option (Mac) or Alt (Win) key when you select split source (button or menu command) to rotate the orientation of the two views.
To create the split screen view, hold down the OPTION/ALT key and click on the split screen icon in the bottom left corner. Click for larger image.