void set_visible_window(bool visible_window
You may use this method to set whether the child window of the event
box will be visible or not. An invisible child window will only
receive events and nothing else. However if the child window is
visible, it will act as a parent window for the widget that was added
to the event box.
You may make the child window invisible if you wish to trap events
only. Visible child windows are useful when you want to set the
background for the box to a different color or draw on it.
The default behavior is to make the child window visible. You may
pass false as a parameter to the method if you wish
to make the window invisible.