See the Backwards Issues topic and the Control keyword topic in the help file.
You will need to change:
Code:
ItmPanel0.Add(ZZ_Tbls_FileSetFromFileName(FileName(ArlFiles.Item(i))))
To:
Code:
Control("ItmPanel0",ComboBox).Add(ZZ_Tbls_FileSetFromFileName(FileName(ArlFiles.Item(i))))