We talked about this in our Mendix in an International environment knowledge network day. The way this was solved is to create an entity with the warning messages. Then you could solve it with the method described in the post about this subject.
Regards,
Ronald
I have used the following trick to abuse the mendix framework a little. What I do is the following:
This way you abuse the mendix framework a little, but it should be what you need, and without implementing any custom.
Regards,
Ferry