gtk/gtk.go
func (v *Notebook) PageNum(child IWidget) int {
	c := C.gtk_notebook_page_num(v.native(), child.toWidget())
	return int(c)
}
func (v *Notebook) PageNum(child IWidget) int {
	c := C.gtk_notebook_page_num(v.native(), child.toWidget())
	return int(c)
}
// PageNum() is a wrapper around gtk_notebook_page_num().