How to show a secondary form on taskbar using FMX C++?

Question

I'm with a little problem when trying to show more than one form on taskbar on the same time. I found I need to use the following:

WS_EX_APPWINDOW

So I search a little bit more about and then found it:

class TForm2 : public TForm
{
__published:    // IDE-managed Components
private:        // User declarations
public:         // User declarations
        __fastcall TForm2(TComponent* Owner);
        void __fastcall CreateParams(Controls::TCreateParams &Params);

};

void __fastcall TForm2::CreateParams(Controls::TCreateParams &Params)
{
  TForm::CreateParams(Params);
  Params.ExStyle   = Params.ExStyle | WS_EX_APPWINDOW;
  Params.WndParent = ParentWindow;
}

However that function works just with VCL (TCreateParams is not a member of Fmx::Controls).

So, I search a little bit more again and found it (This function goes at OnCreate form function):

SetWindowLong(Handle, GWL_EXSTYLE, WS_EX_APPWINDOW); 

But I got something wrong saying the following:

[bcc32 Error] Codigo.cpp(19): E2034 Cannot convert 'TWindowHandle * const' to 'HWND__ *'
  Full parser context
    Codigo.cpp(18): parsing: void _fastcall TfrmCodigo::FormCreate(TObject *)
[bcc32 Error] Codigo.cpp(19): E2342 Type mismatch in parameter 'hWnd' (wanted 'HWND__ *', got 'TWindowHandle *')
  Full parser context
    Codigo.cpp(18): parsing: void _fastcall TfrmCodigo::FormCreate(TObject *)

Do you know any other alternative to do this? If you can help me or not, since now, thanks A LOT!

Answer 1

The code snippets you have shown are for VCL only.

FireMonkey does not allow you to customize the creation of a Form's HWND like VCL does. The HWND creation is hidden behind a private interface that FireMonkey uses internally ( TPlatformWin.CreateWindow() ). That is why there is no CreateParams in FireMonkey.

However, you can still access the HWND, but only after it has been created. There is a WindowHandleToPlatform() function (which replaces the older FmxHandleToHWND() function), and a FormToHWND function (which uses WindowHandleToPlatform() internally). All of these functions are Windows-specific, so you have to wrap them with an #ifdef if you are writing FireMonkey code that runs on multiple platforms.

Try this:

#ifdef _Windows
#include <FMX.Platform.Win.hpp>
#endif

...

#ifdef _Windows
//HWND hWnd = FmxHandleToHWND(Form2->Handle);
//HWND hWnd = WindowHandleToPlatform(Form2->Handle)->Wnd;
HWND hWnd = FormToHWND(Form2);
if (hWnd != NULL)
{
    LONG Style = GetWindowLong(hWnd, GWL_EXSTYLE); // <-- don't forget this step!
    SetWindowLong(hWnd, GWL_EXSTYLE, Style | WS_EX_APPWINDOW); 
}
#endif

Also see:

example of embarcadero WindowHandleToPlatform c++