In my application, two forms, form1 and form2 are created in different thread.
I create another form, say form3, in same thread of form1.
When I start my application, from1 and form2 are invoked.
There is one button on form1 to start form3 (form3.show).
See following steps:
1. Click button on form1, form3 is displayed(TopMo st property is True).
...