Actually, it may be more complicated than that. And in line with the typical ways of the world, what you're complaining about may actually be an attempt at feature.
There's at least one LIT command (COMPIL) and possibly others, that automatically turn on the vertical scroll bar when they detect that something of potential interest has scrolled off the top of the screen. (This is in response to people complaining that there weren't able to see important stuff before it scrolled away.) So think of it as a feature! And remember: it probably doesn't affect any end-user since they wouldn't be working at the dot prompt. Plus, you can also use the keyboard shortcut CTRL-SHIFT-UP to toggle the scroll bar on and off (and CTRL-UP / CTRL-DOWN to scroll up/down).
