Most text editors can be split into two horizontal views, two vertical views, or 4 split views. This allows you to simultaneously see up to 4 different areas of the same document without having to scroll back and forth.
Select Window -> Split Horizontally to create two horizontal views.
Select Window -> Split Vertically to create two vertical views.
Select both options to create four views.
Position the cursor over the area between two views and it will change to a resizing cursor. You may then click-and-drag that area to adjust the size of two adjacent views. When four-way split is active, you may position the cursor over the middle intersection of all four views to resize all areas simultaneously.
Tip: Double-click the resize area to quickly turn off splitting for the adjacent views.
You may also split your editor view using the special grippers located above the vertical scrollbar and to the left of the horizontal scrollbar. Click and drag these respective grippers to split your view.