mm-handle-set-external-undisplayer
mm-handle-set-external-undisplayer is a compiled Lisp function in `mm-decode.el
'.
(mm-handle-set-external-undisplayer HANDLE FUNCTION)
Set the undisplayer for HANDLE to FUNCTION.
Postpone undisplaying of viewers for types in
`mm-keep-viewer-alive-types'.