Thanks for pointing out SetYesNoCancelLabels().
I believe I now understand how to solve 2a and 2b
in the original submission.

I'll retest it in LMI a.s.a.p. but I believe I did test it there and didn't see any problems.

As for the custom icons, I should have explained it better, sorry: the way you do it is not by adding icons but by changing labels of the existing ones using wxMessageDialog::SetOkCancelLabels() (or SetYesNoCancelLabels() if you need 3 buttons). E.g. see the example of a custom log target defined in the dialogs sample:

class MyLogGui : public wxLogGui
{
private:
    virtual void DoShowSingleLogMessage(const wxString& message,
                                        const wxString& title,
                                        int style)
    {
        wxMessageDialog dlg(NULL, message, title,
                            wxOK | wxCANCEL | wxCANCEL_DEFAULT | style);
        dlg.SetOKCancelLabels(wxID_COPY, wxID_OK);
        dlg.SetExtendedMessage("Note that this is a custom log dialog.");
        dlg.ShowModal();
    }
};

This remaps "Ok" button to "Copy" and "Cancel" to "Ok" and changes their labels accordingly as well as adds an extended message (which could be used to provide some guidance to the user in LMI case) to all single message log message boxes.

I've just realized that I forgot to update this ticket even although I had addresses these problems in wx 2.9 branch:

(1) This should work out of the box now, i.e. with nothing special to do. In particular the exec sample test mentioned below passes now.
(2) There is still no such flag nor button by default but arbitrary buttons can be added to the message box now and we can decide to add a "Copy" button to all LMI message dialogs if needed.

I'm marking this "Ready for test" because of (1), please let me know if you'd like me to implement the rest of (2) as well.

Thanks!

See the thread beginning here:

  http://lists.nongnu.org/archive/html/lmi/2007-06/msg00004.html

which describes enhancements or an alternative to
wxMessageBox() to meet the following needs:

(1) Display a really long string, such as might arise from
concatenating the stdout and stderr output of a failing
system command. That's just one use case; the general case
would be a '\n'-delimited string argument, and the goal is
to let the user read all the contents, e.g. by scrolling.

Here is an acceptance test for my low-resolution screen
(if this happens to fit on yours in either dimension,
then stretch it so it doesn't):

  std::string s = "0123456789";
  s += s;
  s += s;
  s += s;
  s += s;
  std::string t = "\n0\n1\n2\n3\n4\n5\n6\n7\n8\n9";
  s += t + t + t + t + t;
  wxMessageBoxAlternative // A better name can be chosen.
      (s
      ,"testcase"
      ,wxICON_ERROR
      ,wxTheApp->GetTopWindow()
      );

(2) Add a flag such as wxSHOW_COPY_BUTTON that would:

(a) Visually inform the user that such a facility is
available. On msw, Ctrl-C does this, but few people know
that, and I have received screen-print bitmaps in email
that use hundreds of kilobytes just to show me a brief
text diagnostic. This would copy the entire (potentially
lengthy) string to the clipboard, because that's easier
for users than writing it to a file that they'd have to
find and open.

(b) Improve on what Ctrl-C does on msw by filtering out
"---------------------------" lines and button names.