无法设置子窗口透明度

如何解决无法设置子窗口透明度

我试图让子窗口透明，但没有用。

这是我的代码：

    XVisualInfo xvinfo;
    XMatchVisualInfo(dpy,DefaultScreen(dpy),32,TrueColor,&xvinfo);
    XSetwindowAttributes attr;
    attr.colormap = XCreateColormap(dpy,DefaultRootwindow(dpy),xvinfo.visual,AllocNone);
    attr.border_pixel = 0;
    attr.background_pixel = 0x80800000; // Red,semi-transparent

    Window window = XCreateWindow(dpy,winParent,width,height,xvinfo.depth,InputOutput,CWColormap | CWBorderPixel | CWBackPixel,&attr);

    double alpha = 0.8;
    unsigned long opacity = (unsigned long)(0xFFFFFFFFul * alpha);
    Atom XA_NET_WM_WINDOW_OPACITY = XInternAtom(dpy,"_NET_WM_WINDOW_OPACITY",False);
    XChangeProperty(dpy,window,XA_NET_WM_WINDOW_OPACITY,XA_CARDINAL,PropModeReplace,(unsigned char *)&opacity,1L);