Virtualize showing/hiding the pages in wxBookCtrlBase.

No real changes, just make it possible to change how the pages are hidden and
shown in the derived classes. This is not used by any of them yet, but will be
used by wxSimplebook soon.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@72406 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/common/bookctrl.cpp

@@ -476,11 +476,11 @@ int wxBookCtrlBase::DoSetSelection(size_t n, int flags)
         if ( !(flags & SetSelection_SendEvent) || allowed)
         {
             if ( oldSel != wxNOT_FOUND )
-                m_pages[oldSel]->Hide();
+                DoShowPage(m_pages[oldSel], false);
 
             wxWindow *page = m_pages[n];
             page->SetSize(GetPageRect());
-            page->Show();
+            DoShowPage(page, true);
 
             // change selection now to ignore the selection change event
             UpdateSelectedPage(n);