The behavior of a mouse is normally determined by the settings of the mouse thus not determined by Writer.
Additionally you did not specify your OS and what exactly you are doing, e.g. are you pressing a mouse button while moving the mouse etc.
Using the highlighting tool also my Writer files (Windows XP) scrolls as soon as I just move the cursor outside of the text window. But the scrolling is not very smooth and for my current feeling not very consistent. Sometimes I can go to the next or previous page and sometimes I cannot.
Next I look into the help file and help wiki and search for information about scrolling settings within LibO or Writer but could not find anything. Therefore, I currently assume that the scrolling behavior is controlled by the OS and mouse settings. I would happily be wrong with me statement when we could get an answer on where to control the scrolling behavior in Writer to make is smoother or to turn it on and off.