How on earth does anyone manage to compile wxwindows programs?

[Hendrik Boom <hendrik@pooq.com>]

While compiling an example from the wxwindows tutorial, I get

g++ -I/usr/lib/wx/include/base-2.4/ wxhello.cc -o wxhello
In file included from /usr/include/wx/window.h:27,
                 from /usr/include/wx/toplevel.h:25,
                 from /usr/include/wx/frame.h:23,
                 from wxhello.cc:18:
/usr/include/wx/cursor.h: In constructor `
   wxBusyCursorSuspender::wxBusyCursorSuspender()':
/usr/include/wx/cursor.h:46: error: `wxIsBusy' undeclared (first use this
   function)
/usr/include/wx/cursor.h:46: error: (Each undeclared identifier is reported
   only once for each function it appears in.)
/usr/include/wx/cursor.h:48: error: `wxBusyCursor' undeclared (first use this
   function)
/usr/include/wx/cursor.h:48: error: parse error before `;' token

and pages and pages more error messages, ending with

usr/include/wx/window.h:837: confused by earlier errors, bailing out


Now wxIsBusy is defined in /usr/include/wx/utils.h,
but this file is already included by wx.h.  However, it's conditional on
an
	#if wxUSE_GUI // GUI only things from now on
However, adding a compiler flag _DwxUSE_GUI=1 doesn't seem to help any.

**What have I failed to do?**
And where is it documented?

It never even gets around to my own code, which, by the way, is here:

=====
//
// file name: hworld.cpp
//
//   purpose: wxWidgets "Hello world"
//

// For compilers that support precompilation, includes "wx/wx.h".
#include "wx/wxprec.h"

#ifdef __BORLANDC__
    #pragma hdrstop
#endif

#ifndef WX_PRECOMP
    #include "wx/wx.h"
#endif

#include <wx/frame.h>

class MyApp: public wxApp
{
    virtual bool OnInit();
};

class MyFrame: public wxFrame
{
public:
    MyFrame(const wxString& title, const wxPoint& pos, const wxSize& size);

    void OnQuit(wxCommandEvent& event);
    void OnAbout(wxCommandEvent& event);

private:
    DECLARE_EVENT_TABLE()
};

enum
{
    ID_Quit = 1,
    ID_About,
};
BEGIN_EVENT_TABLE(MyFrame, wxFrame)
    EVT_MENU(ID_Quit,  MyFrame::OnQuit)
    EVT_MENU(ID_About, MyFrame::OnAbout)
END_EVENT_TABLE()

IMPLEMENT_APP(MyApp)

bool MyApp::OnInit()
{
    MyFrame *frame = new MyFrame( "Hello World", wxPoint(50,50), wxSize(450,340) );
    frame->Show( TRUE );
    SetTopWindow( frame );
    return TRUE;
}

MyFrame::MyFrame(const wxString& title, const wxPoint& pos, const wxSize& size)
       : wxFrame((wxFrame *)NULL, -1, title, pos, size)
{
    wxMenu *menuFile = new wxMenu;

    menuFile->Append( ID_About, "&About..." );
    menuFile->AppendSeparator();
    menuFile->Append( ID_Quit, "E&xit" );

    wxMenuBar *menuBar = new wxMenuBar;
    menuBar->Append( menuFile, "&File" );

    SetMenuBar( menuBar );

    CreateStatusBar();
    SetStatusText( "Welcome to wxWidgets!" );
}

void MyFrame::OnQuit(wxCommandEvent& WXUNUSED(event))
{
    Close( TRUE );
}

void MyFrame::OnAbout(wxCommandEvent& WXUNUSED(event))
{
    wxMessageBox( "This is a wxWidgets' Hello world sample",
                  "About Hello World", wxOK | wxICON_INFORMATION );
}

=====