显示文本框输入消息

Question

is there a way to to display a message: " value * not allowed" when a user is inputing in a textbox.

FilteredTextBoxExtender does not allow u enter a value but there is no message with it.

i can have a Button_click even but that will require me to do changes in my code behind.. and i dont want to do that.

cant modalpopup and filtertextboxextender be used together.

currently i am using this but i cant get a message out of ths

 <cc1:FilteredTextBoxExtender ID="ext_Box_FilteredTextBoxExtender" 
                runat="server" Enabled="True" FilterMode="InvalidChars" FilterType="Custom" InvalidChars="*" 
                TargetControlID="up_Box">
            </cc1:FilteredTextBoxExtender>

Answer 1

I'm not quite sure but I think you are looking for validation.

Look at the ASP.NET validator.

http://msdn.microsoft.com/en-us/library/aa479013.aspx