function disableBtn(btnID, newText) {
    Page_IsValid = null; if (typeof (Page_ClientValidate) == 'function') { Page_ClientValidate(); }
    var btn = document.getElementById(btnID); var isValidationOk = Page_IsValid; if (isValidationOk !== null) {
        if (isValidationOk) { btn.disabled = true; btn.value = newText; }
        else { btn.disabled = false; }
    }
    else { btn.disabled = true; btn.value = newText; }
}