In using windows forms I had come across the Validation Provider from Tommy Noogen at http://www.codeproject.com/KB/validation/validationprovider.aspx

I have found this to be a very useful control. I have converted it to work with VisualWebGUI

Note: Codes are submitted as a .zip file to shorten your download time. After downloading it, you will need a program like Winzip to decompress it.

Terms of Agreement:
By using this code, you agree to the following terms...

1. You may use this code in your own programs (and may compile it into a program and distribute it in compiled format for languages that allow it) freely and with no charge.
2. You MAY NOT redistribute this code (for example to a web site) without written permission from the original author. Failure to do so is a violation of copyright laws.
3. You may link to this code from another website, but ONLY if it is not wrapped in a frame.
4. You will abide by any additional copyright restrictions which the author may have placed in the code or code's description.

See notes on changes that may be required for newer versions of Visual Studio and/or Visual WebGUI in forum thread here (Jul-28-2011)