Include wx/defs.h to get wxUSE_DIRDLG value from it, otherwise it could be undefined, and hence evaluate to 0 (unfortunately without even a warning with some compilers), if this header was the first wx header to be included.
Include wx/defs.h to get wxUSE_DIRDLG value from it, otherwise it could be undefined, and hence evaluate to 0 (unfortunately without even a warning with some compilers), if this header was the first wx header to be included.