Delphi - embedded application scrollbars not visible

Question

Based on the Embedding window into another process question I'm embedding an application which has only a TWebBrowser component on the main form, on my main application. Even I'm embedding it to a TScrollBox component the scroll bars don't appear when the main application is resizing. I've made some research on this issue, but without success. How can I enable the scrollbox's scrollbars?

LE: To clarify the question: Application A is a simple form with an TWebBrowser component on it. Application B, the main application, is embedding application A on a TScrollBox placed on a form, with Align set to alClient. Code for embedding A into B

procedure ShowAppEmbedded(WindowHandle: THandle; Container: TWinControl);
var
  WindowStyle : Integer;
  FAppThreadID: Cardinal;
begin
  /// Set running app window styles.
  WindowStyle := GetWindowLong(WindowHandle, GWL_STYLE);
  WindowStyle := WindowStyle
                 - WS_CAPTION
                 - WS_BORDER
                 - WS_OVERLAPPED
                 - WS_THICKFRAME;
  SetWindowLong(WindowHandle,GWL_STYLE,WindowStyle);

  /// Attach container app input thread to the running app input thread, so that
  ///  the running app receives user input.
  FAppThreadID := GetWindowThreadProcessId(WindowHandle, nil);
  AttachThreadInput(GetCurrentThreadId, FAppThreadID, True);

  /// Changing parent of the running app to our provided container control
  Windows.SetParent(WindowHandle,Container.Handle);
  SendMessage(Container.Handle, WM_UPDATEUISTATE, UIS_INITIALIZE, 0);
  UpdateWindow(WindowHandle);

  /// This prevents the parent control to redraw on the area of its child windows (the running app)
  SetWindowLong(Container.Handle, GWL_STYLE, GetWindowLong(Container.Handle,GWL_STYLE) or WS_CLIPCHILDREN);
  /// Make the running app to fill all the client area of the container
  SetWindowPos(WindowHandle,0,0,0,Container.ClientWidth,Container.ClientHeight,SWP_NOZORDER);

  SetForegroundWindow(WindowHandle);
end;

When resizing the main application(B), the scrollbars of the TScrollBox component from B are not showed and the application A rests at it was set from the begging.

Solution : Based on Kobik's comment the application A is embedded into app B inside a TPanel aligned to alClient inside a TScrollBox. On the OnPanelResize event the following code is run:

  if IsWindow(App_B_WindowHandle) then
    SetWindowPos(App_B_WindowHandle, 0, 0, 0, Panel1.Width, Panel1.Height, SWP_ASYNCWINDOWPOS);

Answer 1

Put a VCL container (eg TPanel ) inside the TScrollbox . and embed the client application inside the Panel. This way the TScrollbox will be able to handle the Panel correctly. You cannot simply Align the embedded application inside a Delphi container. You might want to handle the TPanel.OnResize to adjust a new dimensions for the the embedded application (if needed).

In any case, as you already know, the whole idea is a world of pain.