button_press信号未在子类DrawingArea小部件中发出

Question

我通过继承DrawingArea小部件来创建自定义小部件，它在cairo中绘制一个圆圈。我需要获得圈子点击的坐标。我将以下代码连接到实现信号，我配置为接收按钮

static void my_custom_widget_realize_cb (GtkWidget *widget)
{   
    MyCustomWidget *mycustomwidget = MY_CUSTOM_WIDGET (widget);
    MyCustomWidgetPrivate *priv  = mycustomwidget->priv;
    GtkAllocation allocation;
    GdkWindowAttr attr;
    gint attr_mask;
    GdkWindow *parent_window;

    gtk_widget_get_allocation (widget, &allocation);

    gtk_widget_set_realized (widget, TRUE);

    attr.window_type = GDK_WINDOW_CHILD;
    attr.x           = allocation.x;
    attr.y           = allocation.y;
    attr.width       = allocation.width;
    attr.height      = allocation.height;
    attr.wclass      = GDK_INPUT_ONLY;
    attr.event_mask  = (gtk_widget_get_events (widget) |
                    GDK_KEY_PRESS_MASK      |
                    GDK_BUTTON_PRESS_MASK   |
                    GDK_BUTTON_RELEASE_MASK |
                    GDK_POINTER_MOTION_MASK |
                    GDK_ENTER_NOTIFY_MASK   |
                    GDK_LEAVE_NOTIFY_MASK);


    attr_mask = GDK_WA_X | GDK_WA_Y;

    parent_window = gtk_widget_get_parent_window (widget);

    gtk_widget_set_window (widget, parent_window);
    g_object_ref (parent_window);

    priv->window = gdk_window_new (parent_window, &attr, attr_mask);
    gdk_window_set_user_data (priv->window, mycustomwidget);
}

接收button_press的重写回调未被调用。