GtkWidget::queue_draw
This method is the one to use if you need to force a widget to
redraw itself. Put it into a callback function and determine
an appropriate signal to trigger the redraws.
queue_draw() creates an expose
event, in most situations.
In the event that this method does not have the desired effect, try
calling queue_resize() instead.
If that also fails, you will need to resort to calling
hide() followed immediately by
show() in the callback.