OMG

Comment 1 for bug 619624

Yes. This is little bug. Someone forgot to edit Makefile I think. You need to edit ./OMG/Makefile.am and in PREFERENCES you should do:

REFERENCES = \
 $(NDESK_DBUS_10_LIBS) \
 $(NDESK_DBUS_GLIB_10_LIBS) \
 $(NOTIFY_SHARP_LIBS) \
 System \
 $(GTK_SHARP_20_LIBS) \
 $(GLIB_SHARP_20_LIBS) \
 System.Core \
 System.Drawing

So You need to add System.Drawing at the end of it then run ./autogen.sh once again and everything should be fine :)