In Visual Studio toolbox appeared any strange items. It fortunatelly doesn’t influence on functionality.
What is the reason of it? How to erase it?
It appears in some project only (it is such i big project).
I have Visual Studio 2022, I use MFC Dialogs and I have sources divided to more *.rc files.

Thw main rc file header:

 // Microsoft Visual C++ generated resource script.
//
#include "resource.h"

#define APSTUDIO_READONLY_SYMBOLS
/////////////////////////////////////////////////////////////////////////////
//
// Generated from the TEXTINCLUDE 2 resource.
//
#ifndef APSTUDIO_INVOKED
#include "targetver.h"
#endif
#include "afxres.h"
#include "verrsrc.h"

/////////////////////////////////////////////////////////////////////////////
#undef APSTUDIO_READONLY_SYMBOLS

/////////////////////////////////////////////////////////////////////////////
// Czech (Czech Republic) resources

#if !defined(AFX_RESOURCE_DLL) || defined(AFX_TARG_CSY)
LANGUAGE LANG_CZECH, SUBLANG_DEFAULT

#ifdef APSTUDIO_INVOKED

Second rc file header:

// Microsoft Visual C++ generated resource script.
//
#include "resource_mat.h"

#define APSTUDIO_READONLY_SYMBOLS
/////////////////////////////////////////////////////////////////////////////
//
// Generated from the TEXTINCLUDE 2 resource.
//
#ifndef APSTUDIO_INVOKED
#include "targetver.h"
#endif
#include "afxres.h"
#include "verrsrc.h"

/////////////////////////////////////////////////////////////////////////////
#undef APSTUDIO_READONLY_SYMBOLS

/////////////////////////////////////////////////////////////////////////////
// Czech (Czech Republic) resources

#if !defined(AFX_RESOURCE_DLL) || defined(AFX_TARG_CSY)
LANGUAGE LANG_CZECH, SUBLANG_DEFAULT

#ifdef APSTUDIO_INVOKED

and rc file foot:

#ifndef APSTUDIO_INVOKED
/////////////////////////////////////////////////////////////////////////////
//
// Generated from the TEXTINCLUDE 3 resource.
//
#define _AFX_NO_SPLITTER_RESOURCES
#define _AFX_NO_OLE_RESOURCES
#define _AFX_NO_TRACKER_RESOURCES
#define _AFX_NO_PROPERTY_RESOURCES

#if !defined(AFX_RESOURCE_DLL) || defined(AFX_TARG_ENU)
LANGUAGE 9, 1
#include "afxres.rc"      // Standard components
#if !defined(_AFXDLL)
#include "afxribbon.rc"   // MFC ribbon and control bar resources
#endif
#endif

/////////////////////////////////////////////////////////////////////////////
#endif    // not APSTUDIO_INVOKED

Thanks.