A splitter bar makes it possible for you to see (and edit) different parts of your file simultaneously. Each half of the split window has its own scroll bars (horizontal and vertical) for easy movement through your code in either view.
The splitter appears as a small bar above the upper scroll bar arrow on the right side of a Code Editor window. When you drag the bar downward, you open an additional view of the active document, initially at the beginning of the active document. Use the scroll bars or any relocating command in the Edit menu (such as the bookmark commands or the Edit > Go To command) to move to another location in either display.
You can also split your source file window by using the Window > Split command. When you use this command, the cursor changes to a double-arrow that is located at the top of a Code Editor window. Drag the cursor down to open another view of your file.