Use appropriate initial size for the wrapsizer sample frame

Ensure the frame is big enough to show its contents, otherwise some
controls were truncated and not visible at all initially, at least under
MSW.

samples/wrapsizer/wrapsizer.cpp

@@ -146,6 +146,8 @@ WrapSizerFrame::WrapSizerFrame()
     // Set sizer for the panel
     m_panel->SetSizer(sizerRoot);
 
+    SetClientSize(m_panel->GetBestSize());
+
     Show();
 }