Newbie question about constraints

Ok - I'm just investigating custom constraints, and something's bugging me.

In my applications, I like to make things as easy as possible for the user.
One way to do this is to jump straight to the offending control when they've
clicked OK after entering incorrect data.

So, if my "Price" field has to be bigger than zero, then I'll raise an
EPriceZero exception from the datamodule, and the dialog will catch that, and
automatically jump to the Price edit box before notifying the user of the

Constraints don't seem to let me do that: There's no way I can see to tell
which field raised the exception.

Is it possible for me to do this with constraints?


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