Most browsers don't support Windows icon files.

First of all, with "image/vnd.wap.wbmp ico" you told mediawiki that windows bmp
files are icon files - that's simply wrong. Get your mime detection to work -
under linux, you can set $wgMimeDetectorCommand= "file -bi", that should do it.
Alternatively, get a version of PHP that has either the fileinfo or the
mime_magic extension compiled in. ico files should be tectected as image/x-icon.

Second, ico-files will not be handeled as images by mediawiki, because many
browsers do not support it, and it can't really be scaled. It could be rendered
server-side using imagemagick in theory, but this is suppressed, because ico
files may contain multiple images (for animations, or different ones for
enabled/disabled, etc), and the software can't know which one to use. You can
hack that locally, if you want, by uncommenting the following line in the
canRender function in Image.php:

#|| $mime === 'image/x-icon' #file may be split into multiple parts

HTH

Note that wbmp isn't Windows Bitmap, it's some other format for use with WAP.

The tip with $wgMimeDetectorCommand= "file -bi" was perfect (I overlooked that
for weeks) !

But now a request for small code cosmetics in CVS HEAD:

Add in DefaultSettings.php in that line 266 a semicolon after -bi"

265 $wgMimeDetectorCommand= NULL; # use internal mime_content_type function,
available since php 4.3.0
266 #$wgMimeDetectorCommand= "file -bi" #use external mime detector (linux)

-->
266 #$wgMimeDetectorCommand= "file -bi"; #use external mime detector (linux)

rowan.collins wrote:

(In reply to comment #4)

Add in DefaultSettings.php in that line 266 a semicolon after -bi"

Done.

Hope, that it's okay when I now wontfix this bugzilla.