* libgimp/gimpaspectpreview.c: really use the second parameter of
  gimp_aspect_preview_new (), so plug-ins can now really remember the
  state of the preview between invocations.

* libgimpwidgets/gimpscrolledpreview.c: fix a little typo

* plug-ins/common/channel_mixer.c: fix a warning by using TRUE for a
  boolean value (initial state of the preview) instead of a weird NULL.