MODEST_CACHE_MGR_CACHE_TYPE_DATE_STRING, /* time_t => string */
MODEST_CACHE_MGR_CACHE_TYPE_DISPLAY_STRING, /* gchar* => gchar* */
MODEST_CACHE_MGR_CACHE_TYPE_PIXBUF, /* gchar* => GdkPixbuf */
MODEST_CACHE_MGR_CACHE_TYPE_DATE_STRING, /* time_t => string */
MODEST_CACHE_MGR_CACHE_TYPE_DISPLAY_STRING, /* gchar* => gchar* */
MODEST_CACHE_MGR_CACHE_TYPE_PIXBUF, /* gchar* => GdkPixbuf */