var loginHasHadFocus = false;
function LoginUsernameFocus(sender) {
    if (!loginHasHadFocus) {
        sender.value = '';
        loginHasHadFocus = true;
    }
}

function ToggleCheckboxes(checkBoxClass, selected) {
    $("." + checkBoxClass + " >input:checkbox").each(function() {
        this.checked = selected;
    }); 
}