protected function detab($text)
{
#
# Replace tabs with the appropriate amount of space.
#
# For each line we separate the line in blocks delemited by
# tab characters. Then we reconstruct every line by adding the
# appropriate number of space between each blocks.
$text = preg_replace_callback('/^.*\\t.*$/m', array(&$this, '_detab_callback'), $text);
return $text;
}