We need to include full [io]stream declaration and not just forward declare them to be able to define classes deriving from them. Surprisingly, including just <iosfwd> seems to work under most systems but it does not under IRIX. So include the full <iostream> (or <iostream.h>) to be sure to get what we need. git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@63571 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775