firefox addon - Using l10n (language localized) strings with ARIA -

i'm trying make extension use aria tags through localized strings, explained in mdn. so, have properties file things like:

new_file=new file new_file.arialabel=creates new file 

and then, i'm trying use inside sidebar html code:

<button type="button" class="btn ui-button">   <span class="glyphicon glyphicon-plus"          data-l10n-id="new_file"          aria-label="new_file.ariavaluetext"/> </button> 

the new_file works in span, can read it, not aria label. tryed without specifying aria-label in html, write anything, , doesn't work. missing? in advance!

make sidebar xhtml file. use l10n xhtml localization: https://github.com/noitidart/l10n/tree/xhtml-xul can use technique populate aria- tags.

here's great guide on mdn github link gave you: https://developer.mozilla.org/en-us/add-ons/bootstrapped_extensions#localization_%28l10n%29

here's link l10n html options page (xhtml html localization files) https://github.com/noitidart/l10n/tree/html-options