#11 OS X crash using latest SVN

[Brucey]

SetFont() appears to be called by the Mac framework during the wxFlatNotebook creation.
Since at that point m_pages doesn't exist yet, it bombs out on the line :

m_pages->m_font = ....

The workaround is to skip this if m_pages isn't set yet :

if (m_pages)
m_pages->m_font = font;

:o)