I have some problems with Mantis 0.18.1 localization. It's needed to translate some strings in .php files (not in strings_.txt). List below:

File proj_doc_page.php

print_bracket_link( 'proj_doc_edit_page.php?file_id='.$v_id, 'edit' );

File login_page.php

echo '

<font color="red">WARNING: Plain password authentication is used, this will expose your passwords to administrators.</font>

echo '

<font color="red">WARNING: You should disable the default "administrator" account or change its password.</font>

echo '

<font color="red">WARNING: Admin directory should be removed.</font>