form in form problem

 Hello, I replicated one problem with a smaller test; Please see below:

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
procedure( testforms()
    let( (form)
        form = hiCreateAppForm(
            ?name 'firstForm
            ?formTitle "First Form"
            ?buttonLayout 'OKCancel
            ?fields list( 
               list(hiCreateButton(
                       ?name 'theTestButton
                       ?buttonText "Test Button"
                       ?callback "TestButtonCollback()")  230:10 140:30)
                 )
             )
        hiDisplayForm(form)
        printf("First form is finished; Ok button or Cancel button was pressed;")
    )
)

procedure( TestButtonCollback()
    let( (form2)
        form2 = hiCreateAppForm(
            ?name 'IfxERC_SecondForm
            ?formTitle "Second form"
            ?buttonLayout 'OKCancel
            ?fields list(  
                 list(hiCreateButton(
                        ?name 'uselessButton
                        ?buttonText "Useless button"
                        ?callback "UselessButtonCollback()")  10:100 140:30)
                 )
             )
        hiFormCancel(firstForm)
        hiDisplayForm(form2)
        hiDisplayForm(firstForm)
    )
)

procedure( UselessButtonCollback()
    let( ()
        printf("The useless button was pressed;\n");
    )
)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

In these example I want to open a form (first form), than , pressing a button in this first form (Test button), I want to hide the first form, and showa second form; When this second form is closed I want to show back the first form; But I have a problem; 

Please teste next 2 cases:

First case (non-problematic) :
1:  run testforms() => the "first form" appears;
2: close the form (Ok or Cancel Button) => the form is closed and in ICFB is printed "First form is finished; Ok button or Cancel button was pressed;" This is ok becasue the hiDisplayForm() is finished after Ok/Cancel was pressed;

Second case (problematic) :
1: run testforms() => the "first form" appears;
2: Press "Test Button" button =>"TestButtonCollback" procedure is called; Second form is created (form2); first form is closed ( "hiFormCancel(firstForm)" ) but the string from first procedure is NOT executed !!! ; Second form is displyed;
3: Close (or Ok) second form => second form is closed and first form is backon the screen;
4: Close (or Ok) the first form => the first form is closed;

 After this second case, in ICFB, doesn't appear: "First form is finished; Ok button or Cancel button was pressed;" string from the printf which is called after the first form is closed;  WHY ? 

Why the "hiFormCancel(firstForm)" from the TestButtonCollback() doesn't end the "hiDisplayForm(form)" from the "testforms()" ?

Where am I wrong ?

How can I hide the first form and than bring back again ?

I don't want to set the second form as modal, and I don't want to let both forms (modaless) on the screen;

Thank you,

Adi.