Correct notebook sample layout.

Use a sizer for the frame to make sure its initial and minimal size correspond
to the best size of the panel inside it. Also add a Layout() call on the panel
which was somehow not done initially. And finally don't centre the frame, this
is unnecessary.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@64380 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

samples/notebook/notebook.cpp

@@ -402,10 +402,11 @@ MyFrame::MyFrame()
     RecreateBook();
 
     m_panel->SetSizer(m_sizerFrame);
+    m_panel->Layout();
 
-    m_sizerFrame->SetSizeHints(this);
-
-    Centre(wxBOTH);
+    wxBoxSizer *sizer = new wxBoxSizer(wxVERTICAL);
+    sizer->Add(m_panel, wxSizerFlags(1).Expand());
+    SetSizerAndFit(sizer);
 }
 
 MyFrame::~MyFrame()