Add unit tests checking that the behaviour really corresponds to the documentation too. And also mention that it's not a good idea to have strings differing by case only in wxComboBox anyhow. git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@66442 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775