[webconfig] introduce property sheets. Use them to replace external_resources
CubicWeb.require('ajax.js');
function removeBookmark(beid) {
d = asyncRemoteExec('delete_bookmark', beid);
d.addCallback(function(boxcontent) {
reloadComponent('bookmarks_box', '', 'boxes', 'bookmarks_box');
document.location.hash = '#header';
updateMessage(_("bookmark has been removed"));
});
}