Default Activity ‘Filter on’ to ‘All’ Dynamics CRM 2011 UR12

//default the Activities 'Filter on' to 'All' for Account and Contact for rollup 12 

function filterAllActivities() {
    document.getElementById("navActivities").onclick = function () {
        Mscrm.Details.loadArea(this, "areaActivities");
        document.getElementById("areaActivitiesFrame").onload = function () {
            var entityName = Xrm.Page.data.entity.getEntityName();
            var entity = entityName.charAt(0).toUpperCase() + entityName.substr(1);
            var doc = this.contentWindow.document;
            var filterOn = doc.getElementById("crmGrid_" + entity + "_ActivityPointers_datefilter");
            filterOn.value = "All";
            var evt = document.createEvent("HTMLEvents");
            evt.initEvent("change", false, true);
            filterOn.dispatchEvent(evt);
        };
    };
}