Re: Emacs GTK scroll-bar flickering

[Richard Stallman <rms@gnu.org>]

    When lines aren't available, Emacs uses characters instead.  But
    every character added or deleted changes the thumb because the ratio
    between total number characters in the file and the number of characters
    shown changes.  Thus, Emacs updates the thumb a lot more than a
    line based application.  When the scroll bar is bad at updating
    for small changes like this, flicker occurs.

If the cause is really that, perhaps Emacs should remember the last
size and position values used for the scroll bar, and report them to
GTK instead of the real values, as long as the real size and position
have not changed by more than 1% from those saved values.