This example creates a new `Display` and `Window` using the common Xlib functions `XOpenDisplay` and `XCreateSimpleWindow`. It then calls a helper function `attach_cursor` that uses both XCB and Xlib facilities to set the cursor of the provided `Window` to whatever shape the client provides (in this case a question mark with an arrow as defined by `XC_question_arrow`).

    #include <X11/Xlib-xcb.h>
    #include <X11/cursorfont.h>
    #include <unistd.h>
    
    void attach_cursor(Display *dpy, Window w, int shape)
    {
        static const int fgred = 0, fggreen = 0, fgblue = 0,
            bgred = 0xFFFF, bggreen = 0xFFFF, bgblue = 0xFFFF;
    
        xcb_connection_t *c = XGetXCBConnection(dpy);
        xcb_cursor_t cursor = xcb_generate_id(c);
        xcb_window_t window = (xcb_window_t) w;
        xcb_font_t font = xcb_generate_id(c),
               *mask_font = &font; /* An alias to clarify what is being passed
                                      to XCBCreateGlyphCursor. */
    
        xcb_open_font(c, font, sizeof("cursor"), "cursor");
        xcb_create_glyph_cursor (c, cursor, font, *mask_font, shape, shape + 1,
                             fgred, fggreen, fgblue, bgred, bggreen, bgblue);
        XDefineCursor(dpy, window, cursor);
        xcb_free_cursor(c, cursor);
        xcb_close_font(c, font);
    }
    
    int main(void)
    {
        static const int DEPTH = 0, X = 0, Y = 0, BORDER_WIDTH = 1;
        static const size_t WIDTH = 150, HEIGHT = 150;
    
        Display *dpy;
        int screen_num;
        unsigned int bordercolor, bgcolor;
        Window window;
    
        dpy = XOpenDisplay(NULL);
        screen_num = DefaultScreen(dpy);
        bordercolor = BlackPixel(dpy, screen_num);
        bgcolor = WhitePixel(dpy, screen_num);
        window = XCreateSimpleWindow(dpy, RootWindow(dpy, screen_num), X, Y, WIDTH,
                                     HEIGHT, BORDER_WIDTH, bordercolor, bgcolor);
    
        attach_cursor(dpy, window, XC_question_arrow);
        XMapWindow(dpy, window);
        XSync(dpy, 0);
    
        pause(); /* Hit C-c to break out of this loop. */
    
        return 0;
    }
    
Suppose that the `attach_cursor` function was to be ported entirely to use XCB's functionality. How could the pointer's cursor be set to the specified symbol without using `XDefineCursor`?

# See Also

- [[XcbPorting]]
- [[MixingCalls]]