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Maybe we could use lower case windows.h only if __MINGW32__ is defined?

It's still a fudge that might break. Isn't it better to get to the bottom of the (MinGW-)problem (other headers are affected as well, as Windows.h is not the only header starting with a capital)?

That's right, we could look at all #includes in boost. I have just checked and both mingw and mingw-w64 have only fully lower case headers. Frédéric