Re: [h-e-w] compare-windows odd behavior

[Eli Zaretskii]

> Date: Fri, 29 Jun 2012 04:05:15 -0400
> From: MBR <address@hidden>
> 
> In one Emacs window I have a buffer containing the following text:
> 
>     uarg=-Ujdbc:odbc:PLDBKSM-20120620
>     #uarg=-Ujdbc:odbc:PLDBMartin-20120124
> 
> The buffer displayed by the other Emacs window contains:
> 
>     jdbcURL=jdbc:odbc:PLDBKSM-20120620
> 
> I'd intended to position the cursors in each window at the beginning of 
> each jdbc URL so I could compare them, but I forgot to, o the cursor was 
> on the first character in each window when I ran 'M-x compare-windows'.  
> Since the cursor in the first window was positioned on the "u" and in 
> the second window it was positioned on the "j", compare-windows should 
> have beeped and stopped without moving either cursor.  Yet, much to my 
> surprise, the cursor (shown below as a '^') in the first window advanced to:
> 
>     uarg=-Ujdbc:odbc:PLDBKSM-20120620
>     #uarg=-U^jdbc:odbc:PLDBMartin-20120124
> 
> and in the second window it advanced to:
> 
>     jdbcURL=^jdbc:odbc:PLDBKSM-20120620
> 
> This doesn't make any sense.  Furthermore, since I still have 21.3.1 
> installed, I tried the same thing in the old version, and it behaved as 
> I expected - i.e. compare-windows beeped without moving either cursor.

Didn't it also display the chunk between "j" and the cursor in some
non-default background color?  This shows you where the
synchronization point is, and the text that is different between the
two windows.

IOW, this is a new feature, see the variable compare-windows-sync.  If
you dislike this behavior, set that variable to nil, and you will get
the old behavior.

This change was announced in NEWS of Emacs 22.1:

  *** M-x compare-windows now can automatically skip non-matching text to
  resync points in both windows.