Cryptical display of STL classes in the VC++ debugger

While in the old days of Visual Studio 6 checking the contents of STL classes in the debugger was rather cryptical, Visual Studio 2005 made this part of debugging STL objects a piece-of-cake. An instance of the STL map class nicely lists its entries

Well, up to a certain day at least, when, coinciding with the installation of some Visual Studio Addin, suddenly that long gone VS 6 display of STL objects surfaced again.

Some analysis led to a modified 'autoexp.dat' file as the cause. This file is located in the 'Common7/Packages/Debugger' subdirectory of Visual Studio 2005. It contains rules for expanding objects in the variables and watch views of Visual Studio, so-called 'visualizers'. All visualizers for STL classes had disappeared. Apparently the installed VS addin had been a little bit over ambitious when adding its own classes, removing others on the way. After adding the STL visualizers to the file from a backup, the nice list view of the map contents was back again.