master 195bceed: Supplement documentation

[Ikumi Keita]

branch: master
commit 195bceed828c7a16bed9c63a2db08ec1667a8264
Author: Ikumi Keita <ikumi@ikumi.que.jp>
Commit: Ikumi Keita <ikumi@ikumi.que.jp>

    Supplement documentation
    
    * doc/preview-latex.texi (The Emacs interface):
    * preview.el.in (preview-leave-open-previews-visible):
    Adjust and enhance the explanation of the new customize option.
---
 doc/preview-latex.texi | 7 ++++++-
 preview.el.in          | 8 +++++++-
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/doc/preview-latex.texi b/doc/preview-latex.texi
index 0c1fb730..0bce9747 100644
--- a/doc/preview-latex.texi
+++ b/doc/preview-latex.texi
@@ -674,7 +674,12 @@ current point should be temporarily opened.  Default value 
is @code{nil}.
 
 @item preview-leave-open-previews-visible
 This boolean variable determines whether to leave preview images visible
-(above their generating TeX code) when they are opened.
+when they are opened.
+
+There is a side effect in enabling this option.  The preview image doesn't
+turn into construction sign temporarily when you edit the underlying
+@LaTeX{} code and regenerate the preview; it is just replaced by updated
+image when ready.  This behavior suppresses flicker in the appearance.
 
 @end vtable
 
diff --git a/preview.el.in b/preview.el.in
index 1f65f728..a2c0235d 100644
--- a/preview.el.in
+++ b/preview.el.in
@@ -1213,7 +1213,13 @@ is located."
 (defcustom preview-leave-open-previews-visible nil
   "Whether to leave previews visible when they are opened.
 If nil, then the TeX preview icon is used when the preview is opened.
-If non-nil, then the preview image is moved above the text."
+If non-nil, then the preview image remains visible.  In either case, the
+TeX code appears either below or to the right of the displayed graphic.
+
+If you enable this option, the preview image doesn't turn into
+construction sign temporarily when you edit the underlying LaTeX code
+and regenerate the preview; it is just replaced by updated image when
+ready.  This behavior suppresses flicker in the appearance."
   :group 'preview-appearance
   :type 'boolean)