Ok, so, the issue is that there is no Scroll Bar that is available to the user. Creating the control itself is somewhat trivial.
However, the content inside the windows was not set up for scrolling, so the mechanism will have to be put in. There's a couple of scrolling methods that we can go with:
Scrolling is achieved by sharply moving line by line, or character by character. Easy to implement with existing gr functions.
Scrolling is achieved by smoothly moving the text pixel by pixel. Text and other content is clipped to be shown only within the borders. This may be tricky for me to do, because I haven't found any gr function that'll do something like this. The_E and m|m have suggested using Render-to-Texture of the text/content, painting it to a quad, and then scroll the texture.
Smooth scrolling, but the text "rolls" around the corners like you'd see on a marque, or belt. This can be achieved by manipulating quads the text is painted on so that they will tilt when they get to some predefined position away from the border.