How to get the the value of the of a textBox with TextBoxWatermarkExtender

[k99rs]

I have an application that where i have a an Asp textBox and i added TextBoxWatermarkExtender to it.

<asp:TextBox ID="txtCellNo" runat="Server" /><br />
<ajax:TextBoxWatermarkExtender ID="TextBoxWatermarkExtender4" BehaviorID="CellNoBehavior" TargetControlID="txtCellNo"
    runat="server" WatermarkText="Cell No.">
</ajax:TextBoxWatermarkExtender>

Because i have the page constantly postpage the TextBoxWatermarkExtender Blinds everytime it does a Postback. So i added this to javacript to the page.

function pageLoad() {
    $find('CellNoBehavior')._onSubmit = function () { };
}

The above code prevent it from blinking on every postback. Also this above javascript did not allowed the textBox to PostBack to the code behind when i click the search button. Without the above javascript function i can get the value of the textbox when i click the search button.

I want to get the value of the value of the textbox when i click the button. and also at the have the that when the page postback on an interval of the timer on this page. dont let the watermark blinks.

Can anyone help me out with this? I would really appreciate it.