Витез said:
His brother Andrew called himself "herceg of Dalmatia and Croatia" and 1196. he attacked Dalmatia,but he had no sucess.After unsucessfull attack on Dalmatia,Andrew attacks Hum.He was defeated by ban Perdika.After his return to Hungary,Andrew called himself "duke of Hum",although he was defeated.It seems that it was ordinary thing in that time with hungarian kings,to "invent" titles for themselfs
.
This is a false interpretation.
Dalmatia and Croatia was sometimes used as a learning province for future heirs.
When Béla III was a hostage (or fosterling, chose one
) at the court of Manuel Komnenos, the emperor attacked Hungary, and captured the area. When Béla III became hungarian king, and Manuel died, he took back that territory.
The fact that the area changed hands frequently (parts were under serbian occupation too) doesn't mean that the practice to nominate the heir as Dalmatian and Croatian duke is "invented".