invalidate best size of the book controller too when the pages are added/removed, this fixes a lot of sizing problems with treebook

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@43027 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/generic/treebkg.cpp

@@ -258,8 +258,6 @@ bool wxTreebook::DoInsertSubPage(size_t pagePos,
 
     wxTreeItemId newId = tree->AppendItem(parentId, text, imageId);
 
-    tree->InvalidateBestSize();
-
     if ( !newId.IsOk() )
     {
         (void)wxBookCtrlBase::DoRemovePage(newPos);