The Split Window feature allows you to split the window into several panes and view different parts of your document at the same time. You split windows into panes using pane tool.
To split a window:
Click on the panel tool and drag it to the desired split position. When you release the mouse button, the document will show a pane divider. The pane has its own scroll bars. You can split a window into a maximum of three horizontal and three vertical panes (a total of nine panes). To remove a split, click and drag the pane tool back to its original position, until the pane divider disappears.