无法在C中使用XCB绘制多边形

#include <X11/Xlib.h>

int main() {
    Display *display = XOpenDisplay(NULL);
    Window window = XCreateSimpleWindow(display, DefaultRootWindow(display), 0, 0, 500, 500, 0, 0, 0);
    XSelectInput(display, window, ExposureMask | KeyPressMask);
    XMapWindow(display, window);

    GC gc = XCreateGC(display, window, 0, NULL);
    XSetForeground(display, gc, BlackPixel(display, DefaultScreen(display)));

    XEvent event;
    while (1) {
        XNextEvent(display, &event);
        if (event.type == Expose) {
            XPoint points[] = {{100, 100}, {200, 200}, {300, 200}, {400, 100}};
            int npoints = sizeof(points) / sizeof(points[0]);
            XFillPolygon(display, window, gc, points, npoints, Convex, CoordModeOrigin);
        }
        if (event.type == KeyPress)
            break;
    }

    XFreeGC(display, gc);
    XDestroyWindow(display, window);
    XCloseDisplay(display);

    return 0;
}