onSwitchPage  
  fun onSwitchPage(connectFlags: <Error class: unknown class> = ConnectFlags(0u), handler: (page: Widget, <Error class: unknown class>) -> Unit): <Error class: unknown class>(source)
Emitted when the user or a function changes the current page.
Parameters
connectFlags 
a combination of ConnectFlags
handler
the Callback to connect. Params: page the new current page; pageNum the index of the page