Avoid events when implicitly selecting first wxBookCtrl page.

The first page added to a wxBookCtrlBase-derived control is always selected,
even if "bSelect" argument of AddPage() was false. This is necessary because
a non-empty book control must always have a selection but the "selection
changed" event generated when doing it is unexpected.

Fix this by not generating any events when the first page is implicitly
selected.

Closes #12075.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@65967 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/os2/notebook.cpp

@@ -648,19 +648,7 @@ bool wxNotebook::InsertPage ( size_t          nPage,
         pPage->Show(false);
     }
 
-    //
-    // Some page should be selected: either this one or the first one if there is
-    // still no selection
-    //
-    int nSelNew = wxNOT_FOUND;
-
-    if (bSelect)
-        nSelNew = nPage;
-    else if ( m_selection == wxNOT_FOUND )
-        nSelNew = 0;
-
-    if (nSelNew != wxNOT_FOUND)
-        SetSelection(nSelNew);
+    DoSetSelectionAfterInsertion(nPage, bSelect);
 
     InvalidateBestSize();