When installed on the root of a domain, mantis fail to correctly compute the url path, corrupting the path of css, images and javascript (pages search for '//css/default.css' instead of '/css/default.css').

The file config_defaults_inc.php contains the following code :

Extract the unique directory path of this file relative to the server's documunt root

if ( preg_match( '@'.$t_docroot.'(.*)@', $t_file_path, $t_matches ) ) {
$t_path = dirname( strip_tags( $t_matches[1] ) );
} else {
$t_path = dirname( strip_tags( $_SERVER['PHP_SELF'] ) );
if ( '/' == $t_path || '\' == $t_path ) {
$t_path = '';
}
}

which should be replaced by :

Extract the unique directory path of this file relative to the server's documunt root

if ( preg_match( '@'.$t_docroot.'(.*)@', $t_file_path, $t_matches ) ) {
$t_path = dirname( strip_tags( $t_matches[1] ) );
if ( '/' == $t_path || '\' == $t_path ) {
$t_path = '';
}
} else {
$t_path = dirname( strip_tags( $_SERVER['PHP_SELF'] ) );
if ( '/' == $t_path || '\' == $t_path ) {
$t_path = '';
}
}