ValidationTextBox: can't disable popups for missing/invalid values

[bill]

For ValidationTextBox? there's no way to disable displaying the popup messages. Even setting invalidMessage="" doesn't help.

Maybe this is for A11Y reasons? But especially after #3273 is fixed, it seems like most of the time you would want no message to be displayed, because at least for a simple required=true ValidationTextBox?, it's pretty obvious what the error is, and there's even an icon.

Maybe the default should be to display no message.

Becky, we should assign this to Doug unless thre are A11Y reasons we need the popup? I hope not.

[becky]

I can certainly see making the message for required=true optional, especially since we are adding an error icon and the screen reader will hear the "required" property. I do have some concerns about removing invalid popups since they can provide information about the correct format - people could be pretty confused if they keep getting an error and do not know why. But, if someone has provided good labels and instructions the popups might be overkill so I can see making them optional. We just need to make sure the documentation describes the possible a11y consequences of making them optional. Do we have a place (and more importantly format) to start creating widget documentation?

[doughays]

(In [10439]) Fixes #4154. Check for invalidMessage override.