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<erlref>
<header>
  <copyright>
    <year>2020</year>
    <holder>Ericsson AB. All Rights Reserved.</holder></copyright>
  <legalnotice>
      Licensed under the Apache License, Version 2.0 (the "License");
      you may not use this file except in compliance with the License.
      You may obtain a copy of the License at

          http://www.apache.org/licenses/LICENSE-2.0

      Unless required by applicable law or agreed to in writing, software
      distributed under the License is distributed on an "AS IS" BASIS,
      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
      See the License for the specific language governing permissions and
      limitations under the License.

  </legalnotice>
  <title>wxBookCtrlEvent</title>
</header>
<module>wxBookCtrlEvent</module>
<modulesummary>Functions for wxBookCtrlEvent class</modulesummary>
<description><p>This class represents the events generated by book controls (<seeerl marker="wxNotebook"><c>wxNotebook</c></seeerl>, <seeerl marker="wxListbook"><c>wxListbook</c></seeerl>, <seeerl marker="wxChoicebook"><c>wxChoicebook</c></seeerl>, <seeerl marker="wxTreebook"><c>wxTreebook</c></seeerl>, <seeerl marker="wxAuiNotebook"><c>wxAuiNotebook</c></seeerl>).
      </p><p>The PAGE_CHANGING events are sent before the current page is changed. It allows the program to examine the current page (which can be retrieved with <seemfa marker="#getOldSelection/1"><c>getOldSelection/1</c></seemfa>) and to veto the page change by calling <seemfa marker="wxNotifyEvent#veto/1"><c>wxNotifyEvent:veto/1</c></seemfa> if, for example, the current values in the controls of the old page are invalid.
      </p><p>The PAGE_CHANGED events are sent after the page has been changed and the program cannot veto it any more, it just informs it about the page change.
      </p><p>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.
      </p><p>See: <seeerl marker="wxNotebook"><c>wxNotebook</c></seeerl>, <seeerl marker="wxListbook"><c>wxListbook</c></seeerl>, <seeerl marker="wxChoicebook"><c>wxChoicebook</c></seeerl>, <seeerl marker="wxTreebook"><c>wxTreebook</c></seeerl>, <seeerl marker="wxToolbook"><c>wxToolbook</c></seeerl>, <seeerl marker="wxAuiNotebook"><c>wxAuiNotebook</c></seeerl>
      </p>
  <p>This class is derived (and can use functions) from: 
    <seeerl marker="wxNotifyEvent"><c>wxNotifyEvent</c></seeerl> <seeerl marker="wxCommandEvent"><c>wxCommandEvent</c></seeerl> <seeerl marker="wxEvent"><c>wxEvent</c></seeerl></p>
  
  <p>wxWidgets docs: <url href="https://docs.wxwidgets.org/3.1/classwx_book_ctrl_event.html">wxBookCtrlEvent</url></p>
  </description>
<datatypes>
    <datatype><name name="wxBookCtrlEvent"/></datatype>
    <datatype><name name="wxBookCtrl"/></datatype>
    <datatype><name name="wxBookCtrlEventType"/></datatype></datatypes>

<funcs>
  <func>
    <name name="getOldSelection" arity="1" clause_i="1" since=""/>
    <fsummary>Returns the page that was selected before the change, <c>wxNOT_FOUND</c> if none was selected. </fsummary>
    <desc><p>Returns the page that was selected before the change, <c>wxNOT_FOUND</c> if none was selected. 
      </p></desc>
  </func>
  
  <func>
    <name name="getSelection" arity="1" clause_i="1" since=""/>
    <fsummary>Returns the currently selected page, or <c>wxNOT_FOUND</c> if none was selected. </fsummary>
    <desc><p>Returns the currently selected page, or <c>wxNOT_FOUND</c> if none was selected. 
      </p><p>Note: under Windows, <seemfa marker="#getSelection/1"><c>getSelection/1</c></seemfa> will return the same value as <seemfa marker="#getOldSelection/1"><c>getOldSelection/1</c></seemfa> when called from the <c>EVT_BOOKCTRL_PAGE_CHANGING</c> handler and not the page which is going to be selected. 
      </p></desc>
  </func>
  
  <func>
    <name name="setOldSelection" arity="2" clause_i="1" since=""/>
    <fsummary>Sets the id of the page selected before the change. </fsummary>
    <desc><p>Sets the id of the page selected before the change. 
      </p></desc>
  </func>
  
  <func>
    <name name="setSelection" arity="2" clause_i="1" since=""/>
    <fsummary>Sets the selection member variable. </fsummary>
    <desc><p>Sets the selection member variable. 
      </p></desc>
  </func>
  </funcs>
</erlref>
