var fm_url = 'portal_filesmanager';

function open_fm(callback_name){
    var fm_window  = window.open(fm_url+'?callback='+callback_name, 'Mediatheque', 'toolbar=0, scrollbars=1, location=0, statusbar=0, menubar=0, resizable=1, dependent=1, width=800, height=500');
    if(!fm_window.opener) fm_window.opener = window;
    fm_window.focus();
}