Re: Gtk scrollbar: thumb too short

[Richard Stallman <rms@gnu.org>]

      The appearance of the GTK scrollbar was chosen to provide
    a metaphor for a a pixel based approach.  Exact same appearance with
    different behavior is confusing, 

The same appearance with gratuitous incompatible behavior would be
confusing, but handling overscrolling is an extension, not an
incompatibility.  No matter how the GTK scroll bar handles
overscrolling, this will be an extension to the usual scroll bar
behavior.  It cannot be 100% compatible, but it can be more compatible
or less compatible.

Handling overscrolling the native scroll bar way, by virtually moving
the thumb "out of" the trough, is mostly compatible with the normal
behavior, because it results in the same visual appearance for the
scroll bar for all the non-overscrolled cases.  If you don't
overscroll, everything looks normal.

Handling overscrolling in the current Motif way, by treating the
maximally overscrolled position as "the end", is incompatible in user
terms, because the same scroll position in the buffer corresponds to
a different appearance of the scroll bar.

    I indeed have trouble finding other applications that allow
    overscrolling.  But it is clear that there are people who wish that
    there were more applications that would.  If an application with a
    pixel based philosophy decides to allow overscrolling, it is likely
    that it would want the scrollbar to behave in the way I described
    PixelStuff's scrollbar.

If an app with pixel-based scrolling supports overscrolling, I think
it should display the overscrolling just as Emacs should, by having
the thumb virtually move beyond the end of the trough.

    Visually, the overscrolled piece is a piece of the "document" that you
    can scroll to.

Even for pixel-based apps, I don't think this is a good way to look
at the issue.

    > 3.  Make the GTK scrollbar more customizable so that it can optionally
    >     handle a character based approach and hence behave, within Emacs,
    >     more like the native scrollbar than the pixel based variant of the
    >     GTK scrollbar.

    I think this is the only reasonable solution.

I agree with Miles--this is the only right way.

Owen, would you please implement this facility in the GTK scroll bar?