****************
wx.NotebookEvent
****************

Inheritance diagram for `wx.NotebookEvent`:

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.. inheritance-diagram:: wx.NotebookEvent

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Description
===========

This class represents the events generated by a notebook control: currently, there are two of them. The ``PAGE_CHANGING`` event is sent before the current 
page is changed. It allows the program to examine the current page (which can be retrieved with `GetOldSelection <#GetOldSelection>`_) and to veto the page 
change by calling `event.Veto() <wx.NotifyEvent.html#Veto>`_ if, for example, the current values in the controls of the old page are invalid.

The second event - ``PAGE_CHANGED`` - is sent after the page has been changed and the program cannot veto it any more, it just informs it about the page change.

To summarize, if the program is interested in validating the page values before allowing the user to change it, it should process the ``PAGE_CHANGING`` event, 
otherwise ``PAGE_CHANGED`` is probably enough. In any case, it is probably unnecessary to process both events at once.


.. seealso:: `wx.Notebook <../Widgets/wx.Notebook.html>`_


Derived From
^^^^^^^^^^^^^

* `wx.NotifyEvent <wx.NotifyEvent.html>`_ 
* `wx.CommandEvent <wx.CommandEvent.html>`_ 
* `wx.Event <wx.Event.html>`_ 
* `wx.Object <../Widgets/wx.Object.html>`_ 


Event Handling
^^^^^^^^^^^^^^

==================================================  ==================================================  
Event Name                                          Description
==================================================  ==================================================  
wx.EVT_NOTEBOOK_PAGE_CHANGED(id, func)              The page selection was changed. Processes a ``wx.wxEVT_COMMAND_NOTEBOOK_PAGE_CHANGED`` event.
wx.EVT_NOTEBOOK_PAGE_CHANGING(id, func)             The page selection is about to be changed. Processes a ``wx.wxEVT_COMMAND_NOTEBOOK_PAGE_CHANGING`` event. This event can be vetoed.
==================================================  ==================================================  

Methods Summary
^^^^^^^^^^^^^^^

* `__init__ <#__init__>`_ 
* `GetOldSelection <#GetOldSelection>`_
* `GetSelection <#GetSelection>`_
* `SetOldSelection <#SetOldSelection>`_
* `SetSelection <#SetSelection>`_


Class API
=========

Methods
^^^^^^^


.. method:: __init__(commandType=wx.wxEVT_NULL, id=0, nSel=-1, nOldSel=-1)

   Constructor, used internally.
   
   **Parameters:**

   * `commandType` (eventtype)
   * `id` (int)
   * `nSel` (int)
   * `nOldSel` (int)

   |

   **Returns:**

   `wx.NotebookEvent <wx.NotebookEvent.html>`_
 

-------------

.. method:: GetOldSelection()

   Returns the page that was selected before the change, -1 if none was selected.

   |

   **Returns:**

   `int`


-------------

.. method:: GetSelection()

   Returns the currently selected page, or -1 if none was selected.

   |

   **Returns:**

   `int`


.. note:: under Windows, `GetSelection()` will return the same value as `GetOldSelection()` when called from ``wx.EVT_NOTEBOOK_PAGE_CHANGING``
   handler and not the page which is going to be selected. 

.. note:: Also note that the values of selection and old selection returned for an event generated in response to a call to 
   `wx.Notebook.SetSelection <../Widgets/wx.Notebook.html#SetSelection>`_ shouldn't be trusted as they are currently inconsistent under different 
   platforms (but in this case you presumably don't need them anyhow as you already have the corresponding information).


--------------

.. method:: SetOldSelection(page)

   Sets the id of the page selected before the change.

   **Parameters:**

   * `page` (int)



--------------

.. method:: SetSelection(page)

   Sets the selection member variable.

   **Parameters:**

   * `page` (int)

.. seealso:: `GetSelection <#GetSelection>`_