Scrollbars are one of the most important inventions in computer user
interfaces.  They have been there since day one of the "Windows Icon Menu
Pointer" paradigm, and interestingly, have hardly evolved since then.  Here
is a very quick overview of the history of scrollbars:

  • Proportional scrollbars were a very important innovation that many
    operating systems and UI toolkits took quite a while to implement them (Mac being
    the first offender).  When a scrollbar is not proportional, its "thumb"
    never changes size, regardless of whether you are currently looking at 1% or
    90% of a document.  But history has judged and proportional scrollbars
    are the norm now, even on cell phones.  I believe the reason why Apple
    and other vendors were reluctant offering proportional scrollbars was
    because they were afraid the user would be confused.  It was a
    legitimate concern but Windows (and to some extent, Motif and other X Window
    managers) quickly demonstrated that not only were users quite capable of
    handling the visual information, they actually asked for it.
     

    •  

  • Another improvement that we saw through the years is to group the arrows
    together.  Very few user interfaces ventured there (AmigaOS was one of
    the courageous ones), and yet, the idea is very appealing:  why put the
    up and down arrows so far from each other?  They have a clear icon that
    shows their purpose, so the additional information carried by their position
    in the scrollbar doesn’t really add that much and forces the user to move
    the mouse quite a bit and click on a very narrow button when they was to go
    back and forth between two positions.  Unfortunately, grouped arrows
    never made it in the mainstream and I don’t know of any popular operating
    system that features them.  Quite sad.
     

    Documented scrolling
  • Another very useful innovation that hasn’t received as much exposure as it
    should is what I call "documented scrolling".  It can be seen in a few
    Office programs (the screenshot shows PowerPoint) and Acrobat Reader. 
    The idea is very simple:  as you move the thumb after clicking on it
    and keeping the button pressed, a small tooltip follows your move and lets
    you know in what part of the document you will land if you release the
    button.  Very effective, yet marginal.

The reason for this post is my recent realization that I hardly click on the
arrows any more when I need to move through a lengthy document.

First of all, clicking on these small arrows has always been a challenge that
scores very poorly on
Fitt’s
law scale.  Clicking on small areas of the screen is hard, especially
if your mouse needs to travel over a long distance to get there.

But what is mostly causing this phenomenon is the constant improvement in
pointing devices and techniques that have happened these past years, in order of
discovery:

  • Keyboard shortcuts.  Very important, but hardly used by regular
    users, and sometimes even abandoned by power users because they only work
    well under certain focus conditions.  If you have ever pressed "space",
    expected the document to scroll down and realized that your cursor is in a
    text field, you know what I mean.
     
  • The wheel.  One of the best UI inventions of the past decade. 
    It is by far the most intuitive way to scroll a document and it is
    universally cherished by power and regular users alike.  There is
    simply no way to misunderstand how the wheel works.  Note however that
    it does require certain focus conditions to be met as well, just like
    keyboard shortcuts, but the good news is that you can fix this problem by
    using the same device you are trying to operate (as opposed to keyboard
    shortcuts, which might force you to leave the keyboard, move the mouse,
    click somewhere and then move your hands back to the keyboard).
     
  • The trackpad, which is very efficiently standing in for mouse scrolling
    on laptops.  The trackpad in itself doesn’t really help you scroll
    through a document, but a few innovative ideas have been implemented
    recently by manufacturers that make scrolling with them a breeze, albeit to
    the price of some extra complexity.  I know of two such methods:
     

    • Side scrolling.  Put your finger on the right hand side of the
      trackpad, keep it pressed and move your finger up or down.  This
      method is very effective and traditionally found on Thinkpads.
       
    • Double finger touch.  Touch your trackpad with two fingers
      simultaneously, keep them in contact with the surface and move them up
      or down.  This method is a bit more intuitive than the one above
      because you can touch any part of the trackpad to enable it.

With all this in mind, it’s hard for me to come up with a reason to click on
any of these tiny arrows any more, and yet, I see a lot of people do this on a
regular basis.  The arrows are definitely not going away, so maybe software
vendors should come up with way to make them a bit more friendly, such as maybe
magnifying them as the pointer comes in their vicinity?

How about you, how do you scroll through long documents?