Scrollbar does not 'scroll' when using loading a random external test file

I used a tutorial on this site (thanks!), and tweaked it abit, so that it would load random external files. I have had no problems, except for the fact that when long text files are loaded, the scroll bar does not allow me to scroll. It remains like how it would when a short text file is loaded. Is there a work-around for this? Thanks a million!
(i hope that my post can be comprehended…)

So are you saying that the “short” text files are long enough to need to scroll?

No; the short text files are short enough so as not to require scrolling. As such, the ‘scrolling tab’ on the bar is absent.