Point to the split box at the top of the vertical scroll bar. 
When the pointer changes to a resize pointer,
drag the split bar to the position you want.
At times you may need to see two portions of the main window at the same time. You can do this by following these steps:
Point to the split box at the top of the vertical scroll bar.
When the pointer changes to a resize pointer, drag the split bar to the position you want.
NoteTo return to a single window, double-click the split bar.
While the window is split only one pane is active at a time. To move from one pane to another, click on the white space in the inactive pane. (Do not click on text in the inactive pane, because this can lead to undesired results—relocation of the Phrase box, or other behaviors.)