2
In case someone need this:
This can be solved by editing
\html\modules\system\admin\smilies\smilies.phpedit
lines 131 and 166 (xoops 2.07 reference)
$uploader = new XoopsMediaUploader(XOOPS_UPLOAD_PATH, array('image/gif', 'image/jpeg',
'image/pjpeg', 'image/x-png'), 100000, [b][color=FF0000]120[/color], [color=0000FF]120[/color][/b]);
Just change the red number for the width
and the blue one for the height you want to allow.