A CustomValidator doesn't need to have it's ControlToValidate property set, so

I've just finished reading up on the CustomValidator control and I have a question. In the book I'm reading, it says that a CustomValidator doesn't need to have it's ControlToValidate property set and it gives a few examples of that usage. But in one example where ControlToValidate isn't used, the OnServerValidate function has a timer (5 seconds) that you need to beat by entering your 'answer' into a textbox. If it takes you longer than 5 seconds, the CustomValidator's error message pops 开发者_C百科up next to the textbox (it's like a timed question/answer game) . How did the CustomValidator know to place the message next to the textbox (there's no association between the two, that I know of)? I wanted to test this, so I put a couple more textboxes on the page and the error message always showed up next to the last textbox I placed on the page. Thanks.

The error message shows up at the location of the CustomValidator control, it has nothing to do with the location of the TextBox. Also, if you have a ValidationSummary control on the page, it shows up there as well.