Preventing a negative value

Does anyone have a good way of preventing a user from entering a negative value into a field?
Do you mean line an Input field?
If so i think you can either check the value once you press a submit button or whatever you use to proceed with the application, or maybe you can check for it by adding some condition to the "onchange" property of that Input field. That should verify the value in runtime.

Hope it helps,
Rui Molefas
Gerry -

In the action that handles the input (like your "OK" button), test to see if the value is negative. If so, set the "Valid" property of the widget (should be under the Edit Record -> Widgets -> Name of widget) to "False" and the "ValidationMessage" to something like, "number must be positive".