Tooltip is never shown again after I click on the button [rephrased to reflect edited content ]

#define UNICODE 1
#define _WIN32_WINNT 0x0501
#define WINVER 0x0500
#include <windows.h>
#include <commctrl.h>

/*  Declare Windows procedure  */
LRESULT CALLBACK WindowProcedure (HWND, UINT, WPARAM, LPARAM);

/*  Make the class name into a global variable  */
wchar_t szClassName[ ] = L"CodeBlocksWindowsApp";

HINSTANCE hInst;

ATOM myRegClass()
{
    /* The Window structure */
    WNDCLASSEX wincl;        /* Data structure for the windowclass */
    wincl.hInstance = hInst;
    wincl.lpszClassName = szClassName;
    wincl.lpfnWndProc = WindowProcedure;      /* This function is called by windows */
    wincl.style = CS_DBLCLKS;                 /* Catch double-clicks */
    wincl.cbSize = sizeof (WNDCLASSEX);

    /* Use default icon and mouse-pointer */
    wincl.hIcon = LoadIcon (NULL, IDI_APPLICATION);
    wincl.hIconSm = LoadIcon (NULL, IDI_APPLICATION);
    wincl.hCursor = LoadCursor (NULL, IDC_ARROW);
    wincl.lpszMenuName = NULL;                 /* No menu */
    wincl.cbClsExtra = 0;                      /* No extra bytes after the window class */
    wincl.cbWndExtra = 0;                      /* structure or the window instance */

    /* Use Windows's default colour as the background of the window */
    wincl.hbrBackground = (HBRUSH) COLOR_BACKGROUND;

    /* Register the window class, and if it fails quit the program */
    return RegisterClassEx (&wincl);
}

int WINAPI WinMain (HINSTANCE hThisInstance,
                     HINSTANCE hPrevInstance,
                     LPSTR lpszArgument,
                     int nCmdShow)
{
    HWND hwnd;               /* This is the handle for our window */
    MSG messages;            /* Here messages to the application are saved */

    hInst = hThisInstance;

    if (myRegClass() == NULL)
        return -1;

    /* The class is registered, let's create the program*/
    hwnd = CreateWindow(szClassName, L"Code::Blocks Windows App", WS_OVERLAPPEDWINDOW,
                        CW_USEDEFAULT, CW_USEDEFAULT,
                        544, 375,
                        HWND_DESKTOP,NULL,hThisInstance,NULL);

    /* Make the window visible on the screen */
    ShowWindow (hwnd, nCmdShow);

    /* Run the message loop. It will run until GetMessage() returns 0 */
    while (GetMessage (&messages, NULL, 0, 0))
    {
        /* Translate virtual-key messages into character messages */
        if (IsDialogMessage(hwnd, &messages) == 0)
        {
            TranslateMessage(&messages);
            /* Send message to WindowProcedure */
            DispatchMessage(&messages);
        }
    }

    /* The program return-value is 0 - The value that PostQuitMessage() gave */
    return messages.wParam;
}


HWND addTip(HWND target, wchar_t *tipText)
{
    HWND parentWnd = GetParent(target);
    HWND hwndTip = CreateWindowEx( NULL, TOOLTIPS_CLASS, NULL,
        WS_POPUP | TTS_ALWAYSTIP,
        CW_USEDEFAULT, CW_USEDEFAULT,
        CW_USEDEFAULT, CW_USEDEFAULT,
        parentWnd, NULL, hInst, NULL );

    // Associate the tooltip with the tool.
    TOOLINFO toolInfo = { 0 };
    toolInfo.cbSize = sizeof(toolInfo);
    toolInfo.hwnd = parentWnd;
    toolInfo.uFlags = TTF_IDISHWND | TTF_SUBCLASS;
    toolInfo.uId = (UINT_PTR)target;
    toolInfo.lpszText = tipText;
    SendMessage( hwndTip, TTM_ADDTOOL, 0, (LPARAM)&toolInfo );

    return hwndTip;
}
//SetWindowSubclass

void onPaint(HWND hwnd, WPARAM wParam, LPARAM lParam, COLORREF col)
{
    RECT rc;
    PAINTSTRUCT ps;
    HDC hdc;

    if (wParam == NULL)
        hdc = BeginPaint(hwnd, &ps);
    else
        hdc = (HDC)wParam;

    GetClientRect(hwnd, &rc);
    HBRUSH hbr = CreateSolidBrush(col);
    FillRect(hdc,&rc,hbr);
    DeleteObject(hbr);

    int txtLen, oldMode;
    wchar_t *wndTxt;

    txtLen = GetWindowTextLength(hwnd);
    wndTxt = new wchar_t[txtLen+2];
    GetWindowText(hwnd, wndTxt, txtLen+1);
    oldMode = SetBkMode(hdc, TRANSPARENT);
    DrawText(hdc, wndTxt, -1, &rc, DT_SINGLELINE|DT_CENTER|DT_VCENTER);
    SetBkMode(hdc, oldMode);
    delete wndTxt;

    if (GetFocus() == hwnd)
    {
        RECT focusRect = rc;
        focusRect.left += 4;
        focusRect.top += 4;
        focusRect.right -= 4;
        focusRect.bottom -= 4;
        DrawFocusRect(hdc, &focusRect);
    }

    if (wParam == NULL)
        EndPaint(hwnd, &ps);
}

LRESULT CALLBACK Btn2SubclassProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam, UINT_PTR uIdSubclass, DWORD_PTR dwRefData)
{
    switch (uMsg)
    {
        case WM_ERASEBKGND:
            return 1;

        case WM_PAINT:
            onPaint(hwnd, wParam, lParam,RGB(50,140,87));
            return 0;
    }
    return DefSubclassProc(hwnd, uMsg, wParam, lParam);
}

LRESULT CALLBACK Btn1Proc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
    switch (uMsg)
    {
        case WM_ERASEBKGND:
            return 1;

        case WM_PAINT:
            onPaint(hwnd, wParam, lParam,RGB(87,140,50));
            return 0;
    }

    WNDPROC oldProc;
    oldProc = (WNDPROC)GetWindowLong(hwnd, GWL_USERDATA);
    return CallWindowProc(oldProc, hwnd, uMsg, wParam, lParam);
}

/*  This function is called by the Windows function DispatchMessage()  */
LRESULT CALLBACK WindowProcedure (HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    switch (message)                  /* handle the messages */
    {
        case WM_CREATE:
            {
                HWND hButton = CreateWindow( L"Button", L"test me!",WS_CHILD|WS_VISIBLE|BS_PUSHBUTTON|WS_TABSTOP,50, 50, 75, 23, hWnd, (HMENU)8003, hInst, 0 );
                addTip(hButton, L"test1");
                long origProc;
                origProc = GetWindowLong(hButton, GWL_WNDPROC);
                SetWindowLong(hButton, GWL_USERDATA, origProc);
                SetWindowLong(hButton, GWL_WNDPROC, (long)Btn1Proc);

                HWND btn2 = CreateWindow(L"Button", L"btn2", WS_CHILD|WS_VISIBLE|BS_PUSHBUTTON|WS_TABSTOP, 50, 85, 75, 23, hWnd, (HMENU)8004,hInst,0);
                SetWindowSubclass(btn2,Btn2SubclassProc, 1, NULL);
                addTip(btn2, L"test2");
            }
            return 0L;

        case WM_DESTROY:
            PostQuitMessage (0);       /* send a WM_QUIT to the message queue */
            break;

        default:                      /* for messages that we don't deal with */
            return DefWindowProc (hWnd, message, wParam, lParam);
    }
    return 0;
}