Add "filter changed" event to wxFileCtrl.

Generate an event when the selection in the filter combobox of wxFileCtrl
changes.

Closes #12099.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@64429 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/generic/filectrlg.cpp

@@ -1184,6 +1184,8 @@ void wxGenericFileCtrl::DoSetFilterIndex( int filterindex )
     {
         m_filterExtension.clear();
     }
+
+    GenerateFilterChangedEvent( this, this );
 }
 
 void wxGenericFileCtrl::SetWildcard( const wxString& wildCard )