Thanks for the reply. It is working.
My mistake was that I specified the second argument as MshtmlControl(‘hello world’) instead of #(Mshtml ‘hello world’). I assumed that it was because of a problem of Mshtnl because I could not find CallClass method which UserManual refers to in the section on Dialog – “A Controller that is designed to be used in a Dialog commonly defines a CallClass like …”
Sorry for the silly mistake.