Gtk +鼠标指针离开区域事件

I need to detect when the mouse pointer leaves an area in a GtkNotebook. Normally this is possible with the motion_notify event, but if the pointer is moved fast enough, the event is not triggered. Because this is a certain area of pixels in a GtkNotebook, it is not possible to use a GtkEventBox. What is the proper way to do this?I need to detect when the mouse pointer leaves