function highlightTextbox (textbox) {
     if (textbox.createTextRange) {
        var oRange = textbox.createTextRange();
        oRange.moveStart("character", 0);
        oRange.moveEnd("character", textbox.value.length);
        oRange.select();
    } else if (textbox.setSelectionRange) {
        textbox.setSelectionRange(0, textbox.value.length);
    }
}