wxListbook needs to clean up the wxListCtrl when DeleteAllPages is called.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@28909 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/listbook.h

@@ -109,6 +109,8 @@ public:
     // returns true if we have wxLB_TOP or wxLB_BOTTOM style
     bool IsVertical() const { return HasFlag(wxLB_BOTTOM | wxLB_TOP); }
 
+    virtual bool DeleteAllPages();
+
 protected:
     virtual wxWindow *DoRemovePage(size_t page);