bug#10578: 24.0.92; No png images on OpenSUSE 12.1

[Eli Zaretskii]

> Date: Sun, 22 Jan 2012 19:51:40 +0200
> From: Eli Zaretskii <eliz@gnu.org>
> Cc: 10578@debbugs.gnu.org
> 
> > 1) Why didn't the warnings appear in the echo area instead of just
> > hiding out in the *Messages* buffer?
> 
> Most probably because they are emitted during redisplay, and you
> cannot have anything displayed in the echo area at redisplay time,
> because doing so re-enters redisplay, which will again produce the
> same error message, etc., ad nauseam (a.k.a. infloop).

The message is logged by image_error that has this commentary:

  /* Log error message with format string FORMAT and argument ARG.
     Signaling an error, e.g. when an image cannot be loaded, is not a
     good idea because this would interrupt redisplay, and the error
     message display would lead to another redisplay.  This function
     therefore simply displays a message.  */

(That last "displays" should be "logs".)