WndProc() 함수는 그냥 일반적인 상태에서는 같은 하나의 쓰레드에서 실행되는것이 맞나요?

#include <Windows.h>
#include <iostream>
 
LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
int winMain(HINSTANCE);
 
 
LPCTSTR lpszClass = TEXT("Particle Test");
bool bDone = false;
HINSTANCE g_hInst;
int main(int argc, char **argv)
{
	HINSTANCE hInstance = GetModuleHandle(NULL); 
	g_hInst = hInstance;
	winMain(g_hInst);
}
 
int winMain(HINSTANCE hInstance)
{
	std::cout << hInstance << std::endl;
	HWND hWnd;
	MSG Message;
	WNDCLASS WndClass;
 
	WndClass.cbClsExtra = 0;
	WndClass.cbWndExtra = 0;
	WndClass.hbrBackground = (HBRUSH)GetStockObject(BLACK_BRUSH);
	WndClass.hCursor = LoadCursor(NULL,IDC_ARROW);
	WndClass.hIcon = LoadIcon(NULL, IDI_APPLICATION);
	WndClass.hInstance = NULL;
	WndClass.lpfnWndProc = WndProc;
	WndClass.lpszClassName = lpszClass;
	WndClass.lpszMenuName = NULL;
	WndClass.style=CS_HREDRAW | CS_VREDRAW;
	RegisterClass(&WndClass);
 
	hWnd = CreateWindow(lpszClass,lpszClass,
		WS_OVERLAPPEDWINDOW | WS_CLIPCHILDREN | WS_CLIPSIBLINGS,
		CW_USEDEFAULT,CW_USEDEFAULT,800,600,
		NULL,(HMENU)NULL,hInstance,NULL);
 
	ShowWindow(hWnd, SW_SHOWDEFAULT);
	while(!bDone)
	{
		while(PeekMessage(&Message,NULL,0,0,PM_REMOVE))
		{
			if(Message.message == WM_QUIT)
			{
				bDone = true;
			}else{
				TranslateMessage(&Message);
				DispatchMessage(&Message);
			}
		}
	}
	return (int)Message.wParam;
}
 
 
LRESULT CALLBACK WndProc(HWND hWnd, UINT iMessage, WPARAM wParam, LPARAM lParam)
{
	switch(iMessage){
	case WM_CREATE:
		CreateWindowW(L"button",L"Click Me",WS_CHILD | WS_VISIBLE | BS_PUSHBUTTON,
			20,20,100,25,hWnd,(HMENU)0,g_hInst,NULL);
		return 0;
 
	case WM_COMMAND:
		std::cout << "WM_COMMAN" << std::endl;
		winMain(g_hInst);
		return 0;
 
	case WM_DESTROY:
		PostQuitMessage(0);
		return 0;
	}
	return(DefWindowProc(hWnd, iMessage, wParam, lParam));
}