struct SuilX11Wrapper {
    socket:           GtkSocket,
    plug:             GtkPlug,
    wrapper:          SuilWrapper,
    instance:         SuilInstance,
    idle_iface:       LV2UI_Idle_Interface,
    idle_id:          usize,
    idle_ms:          usize,
    idle_size_req_id: usize,
    initial_width:    usize,
    initial_height:   usize,
    req_width:        usize,
    req_height:       usize,
}

struct SuilX11WrapperClass {
    parent_class:     GtkSocketClass,
}

impl SuilX11Wrapper {
    fn x_window_is_valid (&self) {
        let window:      GdkWindow   = gtk_widget_get_window(self.plug);
        let root:        X11Window   = Some(0);
        let parent:      X11Window   = Some(0);
        let children:    [X11Window] = None;
        let child_count: usize       = 0;
        x_query_tree(window.xdisplay, window.xid, root, parent, children, &mut childcount);
        for i in 0..child_count {
            if children[i] == self.instance.ui_widget {
                x_free(children);
                return true;
            }
        }
        x_free(children);
        return false;
    }
}