Re: Gtk scrollbar: thumb too short

[Richard Stallman]

    It does depend on the UI details.  It could be done by grabbing the mouse 
    (assuming you can know when to do this), but what about clicking on the 
arrows 
    (line down) or the trough (page down)?

The cleanest way to do this is by changing the scroll bar
implementation, giving it a feature of allowing position values all
the way up to the size value.