Windows API'de bir kontrol üzerine geldiğimizde fare resmini değiştirmek için WM_SETCURSOR mesajını kullanabiliriz.

Öncelikle Burada gösterildiği gibi bir Windows API projesi oluşturalım. Projeyle birlikte otomatik olarak oluşturulan main.c dosyası içine aşağıda gösterilen kodları ekleyelim:

HWND hwndStatic, hwndButton;

case WM_CREATE:
     hwndStatic = CreateWindowEx(0, "STATIC", "Static kontrol",
                        WS_CHILD | WS_VISIBLE | SS_LEFT | SS_NOTIFY, 50, 50, 100, 20,
                        hwnd, 0, NULL, NULL);

     hwndButton = CreateWindowEx(0, "BUTTON", "Button",
                        WS_CHILD | WS_VISIBLE, 170, 50, 120, 30,
                        hwnd, 0, NULL, NULL);
     break;

case WM_SETCURSOR:
     if (((HWND)wParam == hwndButton) || ((HWND)wParam == hwndStatic)) {
         SetCursor(LoadCursor (NULL, IDC_HAND));
         return TRUE;
     }
     else return DefWindowProc (hwnd, message, wParam, lParam);
     break;

Yukarıdaki kodları eklediğimizde, main.c dosyasının en son hali aşağıdaki şekilde olacaktır.

main.c

#if defined(UNICODE) && !defined(_UNICODE)
    #define _UNICODE
#elif defined(_UNICODE) && !defined(UNICODE)
    #define UNICODE
#endif

#include <tchar.h>
#include <windows.h>

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

/*  Make the class name into a global variable  */
TCHAR szClassName[ ] = _T("DenemeApp");

HWND hwndStatic, hwndButton;

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 */
    WNDCLASSEX wincl;        /* Data structure for the windowclass */

    /* The Window structure */
    wincl.hInstance = hThisInstance;
    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 */
    if (!RegisterClassEx (&wincl))
        return 0;

    /* The class is registered, let's create the program*/
    hwnd = CreateWindowEx (
           0,                       /* Extended possibilites for variation */
           szClassName,             /* Classname */
           _T("Deneme Uygulaması"), /* Title Text */
           WS_OVERLAPPEDWINDOW,     /* default window */
           CW_USEDEFAULT,           /* Windows decides the position */
           CW_USEDEFAULT,           /* where the window ends up on the screen */
           544,                     /* The programs width */
           375,                     /* and height in pixels */
           HWND_DESKTOP,            /* The window is a child-window to desktop */
           NULL,                    /* No menu */
           hThisInstance,           /* Program Instance handler */
           NULL                     /* No Window Creation data */
           );

    /* 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 */
        TranslateMessage(&messages);
        /* Send message to WindowProcedure */
        DispatchMessage(&messages);
    }

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

/*  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:
             hwndStatic = CreateWindowEx(0, "STATIC", "Static kontrol",
                                WS_CHILD | WS_VISIBLE | SS_LEFT | SS_NOTIFY, 50, 50, 100, 20,
                                hwnd, 0, NULL, NULL);

             hwndButton = CreateWindowEx(0, "BUTTON", "Button",
                                WS_CHILD | WS_VISIBLE, 170, 50, 120, 30,
                                hwnd, 0, NULL, NULL);
             break;

        case WM_SETCURSOR:
             if (((HWND)wParam == hwndButton) || ((HWND)wParam == hwndStatic)) {
                 SetCursor(LoadCursor (NULL, IDC_HAND));
                 return TRUE;
             }
             else return DefWindowProc (hwnd, message, wParam, lParam);
             break;

        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;
}

Program derleyip çalıştırdığımızda aşağıdakine benzer bir ekran görüntüsü karşımıza gelecektir: