case WM_ERASEBKGND: 
    hdc = (HDC) wParam; 
    GetClientRect(hwnd, &rc); 
    SetMapMode(hdc, MM_ANISOTROPIC); 
    SetWindowExtEx(hdc, 100, 100, NULL); 
    SetViewportExtEx(hdc, rc.right, rc.bottom, NULL); 
    FillRect(hdc, &rc, GetStockObject(WHITE_BRUSH)); 

  return 1L; 

case WM_PAINT:
{
    LPPAINTSTRUCT lpps = new PAINTSTRUCT;
    HDC hdc = BeginPaint(hWnd, lpps);
    hbrBackground = CreateSolidBrush(RGB(241, 245, 251));
    FillRect(hdc, &lpps->rcPaint, hbrBackground);
}

HWND CreateNewWindow(int BgColor, HINSTANCE hInstance)
{
HWND hWnd;
WNDCLASSEX wc;
memset(&wc, 0, sizeof(wc));
wc.cbSize=sizeof(WNDCLASSEX);
wc.lpfnWndProc=WndProc;
wc.hInstance=hInstance;
wc.hCursor=LoadCursor(NULL, IDC_ARROW);
switch(BgColor)
{
case 1:
 wc.hbrBackground=CreateSolidBrush(RGB(255, 0, 0));
break;
case 2:
 wc.hbrBackground=CreateSolidBrush(RGB(0, 255, 0));
break;
case 3:
 wc.hbrBackground=CreateSolidBrush(RGB(0, 0, 255));
break;
}
wc.lpszClassName="Window Class";
//далі йде довгий текст який лінь набирати
RegisterClassEx(&wc);
hWnd=CreateWindow();//довгий текст
return hWnd;
}

#include <windows.h>
#define RED 1
#define YELLOW 2
#define BLUE 3
#define GREEN 4
char* alphabet="QWERTYUIOPASDFGHJKLZXCVBNMqwertyuiopasdfghjklzxcvbnm";
char* clname=new char[10];
int counter[10]={0,};
LRESULT CALLBACK WndProc(HWND hwnd, UINT Message, WPARAM wParam, LPARAM lParam);
HWND CreateNewWindow(int BgColor, HINSTANCE hInstance)
{
    int len=strlen(alphabet);
    for (int i=9; i>=0; i--)
    {
        if(counter[i]<len) {
            counter[i]++; break;
        }
    }
    for (int i=0; i<10; i++)
    {
        clname[i]=alphabet[counter[i]];
    }
    MessageBox(0, clname, clname, 0);
    HWND hWnd;
    WNDCLASSEX wc;
    memset(&wc,0,sizeof(wc));
    wc.cbSize         = sizeof(WNDCLASSEX);
    wc.lpfnWndProc     = WndProc; 
    wc.hInstance     = hInstance;
    wc.hCursor         = LoadCursor(NULL, IDC_ARROW);
    
    
    switch(BgColor)
    {
       case RED:
               wc.hbrBackground = CreateSolidBrush(RGB(255, 0, 0));
               break;
       case GREEN:
               wc.hbrBackground = CreateSolidBrush(RGB(0, 255, 0));
               break;
       case BLUE:
               wc.hbrBackground = CreateSolidBrush(RGB(0, 0, 255));
               break;
       default:
            wc.hbrBackground = CreateSolidBrush(RGB(255, 0, 0));    
        
    }
    wc.lpszClassName=clname;
    wc.hIcon= LoadIcon(NULL, IDI_APPLICATION); 
    wc.hIconSm= LoadIcon(NULL, IDI_APPLICATION); 

    if(!RegisterClassEx(&wc)) {
        MessageBox(NULL, "Window Registration Failed!","Error!",MB_ICONEXCLAMATION|MB_OK);
        return 0;
    }
       
       hWnd=CreateWindowEx(WS_EX_CLIENTEDGE,clname,"Caption",WS_VISIBLE|WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT, /* x */
        CW_USEDEFAULT, /* y */
        640, /* width */
        480, /* height */
        NULL,NULL,hInstance,NULL);
        
ShowWindow(hWnd, SW_SHOW);
    return hWnd;
}


LRESULT CALLBACK WndProc(HWND hwnd, UINT Message, WPARAM wParam, LPARAM lParam) {
    switch(Message) {
        case WM_DESTROY: {
            PostQuitMessage(0);
            break;
        }
        
        
        default:
            return DefWindowProc(hwnd, Message, wParam, lParam);
    }
    return 0;
}


int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow) {
    MSG msg; 

    Sleep(10000);
    HWND h=CreateNewWindow(RED, hInstance);
    
    Sleep(10000);
    DestroyWindow(h);
    
    h=CreateNewWindow(BLUE, hInstance); 
    
    Sleep(10000);
    DestroyWindow(h);
    
    h=CreateNewWindow(GREEN, hInstance);
    
    while(GetMessage(&msg, NULL, 0, 0) > 0) { 
        TranslateMessage(&msg); 
        DispatchMessage(&msg); 
    }
    return msg.wParam;
}