Re: gtk scroll bar deficiency

[David Reitter]

On 14 Jun 2007, at 18:21, grischka wrote:

>  Fact is that the toolkits don't enforce neither the one nor
> the other behaviour, but also that no scrollbar toolkit ever
> will magically be able to adjust for the last line of the file
> to stay on bottom of the window if the editor machinery can't
> tell in advance (!) where in the file the last page starts.

And similarly, keeping the editor at a constant size is pretty much  
impossible when the total number of lines in a buffer is unknown.  
That is, of course, very confusing to many users who consider  
switching to Emacs from another editor. To them, the vertical scroll- 
bar has to do with the vertical position in the buffer and the  
vertical dimensions of the window and the buffer. (The horizontal  
scroll-bar, if necessary, handles the horizontal dimensions.) The  
number of characters on each line and shown in the window isn't  
really perceptually salient.

That's something that has been discussed earlier, and it hasn't been  
solved, which was fine when 22.1 was overdue. But now it would be  
nice to have the number of lines available. For the scroll-bar, a  
reasonable estimate would do the job (count line lengths in various  
randomly sampled portions of the buffer if the buffer is big): the  
scroll-bar is a visual tool and not an exact science. The number of  
characters on the last page(s) may need to be precisely determined,  
though