You can do it directly into the widget definition, I think. You add a "required" into your custom properties panel in your widget configuration and express the required value trough EL expression. You are in the context of seam.
If I'm right we check if there is a require value set into the custom properties and we skip the one set in to the standard form of the widget.
If you look the help of the custom properties panel we tell:
Custom properties configuration You
can use this to add additional
properties to the widget, not present
in the form. You can also use custom
property to override the definition of
a widget property configurable through
the form, so as to add a dynamical
definition (which is not possible in
the form when property is a checkbox
like "required" for instance).
Is it what you are looking for ?
