Controlling the Edit Window
By now, you've probably noticed that QBasic's edit window has a couple of extra controls. Along the right side and bottom of the window are scroll bars that enable you to view the parts of a program that are offscreen. You can scroll the program up or down one line at a time in the edit window by clicking the scroll bar's up or down arrow. Likewise, you can scroll left or right one line by clicking the horizontal scroll bar's arrows.
To scroll up or down a full page, click in the vertical scroll bar above or below the scroll thumb. Scrolling horizontally works the same way, except you click in the horizontal scroll bar. Finally, you can move instantly to any place in a program by placing your mouse cursor over the appropriate scroll thumb (the little box inside the scroll bar), holding down the left mouse button and moving the scroll thumb to the position you want.
To scroll a program from the keyboard, use the keyboard's arrow keys or the Page Up and Page Down keys.