All of the callback definitions in core.sys.windows.wingdi starting at line 3949 are missing the "extern(Windows)" attribute.
This has been fixed in git-master. See: https://issues.dlang.org/show_bug.cgi?id=15838 https://issues.dlang.org/show_bug.cgi?id=15958 *** This issue has been marked as a duplicate of issue 15838 ***