How to access the vcl info cross process，how to enum the vcl child control info?

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Delphi

C++11

Here I'm trying to rewrite the VCL method FindControl()(Borland C++ Builder),because the original FindControl function does not support cross process access. According to someone's reference,I wrote the following code

TWinControl* FindControlEh(HWND hwnd);
extern "C" __declspec(dllexport) HWND __stdcall FindControls(HWND hwnd , char* ctrl_name);

TAtom ControlAtom;
char ControlAtomString[512];
DWORD RM_GetObjectInstance;

BOOL WINAPI DllMain(HINSTANCE hinstDLL, DWORD fwdreason, LPVOID lpvReserved)
{
	printf("Load FindControl.dll.");
	switch(fwdreason) {
	case DLL_PROCESS_ATTACH:
	{
		ControlAtom = GlobalAddAtom(ControlAtomString);
        sprintf(ControlAtomString,"ControlOfs%08X%08X",GetModuleHandle(NULL),
													  GetCurrentThreadId());
		RM_GetObjectInstance = RegisterWindowMessage(ControlAtomString);
    }
	break;
	case DLL_PROCESS_DETACH:
		GlobalDeleteAtom(ControlAtom);
	break;
	case DLL_THREAD_ATTACH:
	break;
	case DLL_THREAD_DETACH:
	break;
	}
	return 1;
}
//---------------------------------------------------------------------------
HWND __stdcall FindControls(HWND hwnd , char* ctrl_name)
{
	int index = 0;
	TWinControl* main_controls = FindControlEh(hwnd);
	int ctrls_count = main_controls->ControlCount;
	UnicodeString ctrl_name_unicode(ctrl_name);

	ShowMessage(IntToStr(ctrls_count));
	TWinControl* tmp_control;
	for(index = 0; index (main_controls->Controls[index]);
		if(ctrl_name_unicode == tmp_control->GetNamePath()) {
			//ShowMessage("Find the control" + ctrl_name_unicode);
			return tmp_control->Handle;
		}
	}
	return NULL;
}

TWinControl* FindControlEh(HWND hwnd)
{
	DWORD OwningProcess;
	DWORD hwnd_threadid;
	TWinControl* result = NULL;

	hwnd_threadid = GetWindowThreadProcessId(hwnd , &OwningProcess);

	if( hwnd != NULL && 0 != hwnd_threadid && OwningProcess == GetCurrentProcessId()) {
		if(GlobalFindAtom(ControlAtomString) == ControlAtom) {
			result = (TWinControl*)Pointer(GetProp(hwnd , MakeIntAtomA(PChar(ControlAtom))));
		}
		else result = (TWinControl*)Pointer(SendMessage(hwnd , RM_GetObjectInstance , 0 , 0));
	}
	return result;
}

What I have tried:

I debug the

FindControlEh

method , the result always return null.
here is what I'm doing:
1.I'm not knowing well about the vcl. A lot vcl controls are not standard win32 controls. VCL control's property including some thing like control name which is not accessible.So I'm using the Borland C++ Builder IDE write some methods as interface(DLL), to expose some property of the vcl controls. I'm not known well about the Borland C++ Builder Env. the exposed interfaces in dll will be called in VSC++ env;
2.I'm trying to access all the controls of some other program developed by Borland C++ Builder IDE.cross process. The VCL original function not support cross process access.

FindControl

So I wrote another function,hope to access vcl controls cross process

FindControlEh

It don't work.I don't know what's wrong. give me a hand please.