Compilation failure with wxWidgest 2.8 compatibility

[Mattia Barbon]

  Hi,
when wxWidgets 2.8 compatibility is enabled, compilation fails with:

../../wxWidgets.write/src/generic/odcombo.cpp: In member function 'virtual void wxOwnerDrawnComboBox::DoSetPopupControl(wxComboPopup*)':
../../wxWidgets.write/src/generic/odcombo.cpp:888: error: cannot allocate an object of abstract type 'wxVListBoxComboPopup'
../../wxWidgets.write/include/wx/odcombo.h:72: note:   because the following virtual functions are pure within 'wxVListBoxComboPopup':
../../wxWidgets.write/include/wx/vscroll.h:623: note:   virtual wxCoord wxVarVScrollLegacyAdaptor::OnGetLineHeight(size_t) const

Regards
Mattia