Resources  
  • TextBoxWatermarkExtender Control in AJAXJan 17, 2012. The TextBoxWatermark is an ASP.NET AJAX extender that can be attached to an ASP.NET TextBox control to get watermark behavior. When a watermarked TextBox is empty, it displays a message to the user with a custom CSS Style.
  • AJAX Text Box Watermark ExtenderOct 08, 2008. This article shows how to use two new AJAX Controls, TextBoxWatermarkExtender and ValidatorCalloutExtender in ASP.NET 3.5.