Browser dimensions OnAsyncResize (Priority support)

[valmeras]

I am using Intraweb 15.2.69 with Rad Studio 10.2.3 (C++ Builder)
I am a paid user so I suppose I have access to priority support.
I need to have the right dimensions on the user's browser using the AsyncResize event.
If I try to write the positions of elements using those information they are totally wrongly positioned.
So I wrote the simple code below to see the dimensions returned.

void __fastcall TIWForm1::IWAppFormAsyncResize(TObject *Sender, TStringList *EventParams)
{
        WebApplication->ShowAlert("Height : " + IntToStr(WebApplication->FormHeight));
        WebApplication->ShowAlert("Height : " + IntToStr(WebApplication->FormHeight));

}

I realized that unfortunately the dimensions are not right.
But if I write a JavaScript code using window.addEventListener("resize", ), I get the right dimensions! The problem is that I need to use executeAjaxEvent() to get it on the server side and that slows the rendering of my application.
I had the same problem with Intraweb 14. I upgraded to Intraweb 15 hoping that the issue is resolved. But apparently not!