Known problems
**************

   A number of issues are known concerning the interoperation with
various other software. Some of the known problems can be solved by
moving to newer versions of the problematic software or by simple
patches.

   If you find something not mentioned here, please send a bug report
using `M-x preview-report-bug <RET>', which will fill in a lot of
information interesting to us and send it to the <bug-auctex@gnu.org>
list.  Please use the bug reporting commands if at all possible.

1 Problems with GhostScript
***************************

   Most of the problems encountered come from interaction with
GhostScript.  It is a good idea to have a fairly recent version of
GhostScript installed.  One problem occurs if you have specified the
wrong executable under Windows: the command line version of GhostScript
is called `GSWIN32C.EXE', not `GSWIN32.EXE'.

   When GhostScript fails, the necessary information and messages from
Ghostscript go somewhere.  If GhostScript fails before starting to
process images, you'll find the information at the end of the process
buffer you can see with `C-c C-l'.  If GhostScript fails while
processing a particular image, this image will be tagged with clickable
buttons for the error description and for the corresponding source file.

   The default options configurable with

     `M-x customize-variable <RET> preview-gs-options <RET>'
   include the options `-dTextAlphaBits=4' and `-dGraphicsAlphaBits=4'.
These options have been reported to make GhostScript 5.50 fail, but
should work under GhostScript 6.51 and later.  If you are experiencing
problems, it might help to customize them away.  Of course, this also
takes away the joy of antialiasing, so upgrading GhostScript might not
be the worst idea after all.

   The device names have changed over time, so when using an old
GhostScript, you may have problems with the devices demanded by the
customizable variable `preview-image-creators'.  In that case, make
sure they fit your version of GhostScript, at least the entry
corresponding to the current value of `preview-image-type'.  While not
being best in file size and image quality, setting
`preview-image-creators' to `jpeg' should probably be one of the best
bets for the purpose of checking basic operation, since that device
name has not changed in quite some time.  But JPEG is not intended for
text, but for photographic images.  On a more permanent time scale, the
best choice is to use PNG and complain to your suppliers if either
Emacs or GhostScript fail to properly accommodate this format.

2 Font problems with Dvips
**************************

Some fonts have been reported to produce wrong characters with
preview-latex.  preview-latex calls Dvips by default with the option
`-Pwww' in order to get scalable fonts for nice results.  If you are
using antialiasing, however, the results might be sufficiently nice
with bitmapped fonts, anyway.  You might try `-Ppdf' for another stab
at scalable fonts, or other printer definitions.  Use

     `M-x customize-variable <RET> preview-fast-dvips-command <RET>'
   and
     `M-x customize-variable <RET> preview-dvips-command <RET>'
   in order to customize this.

   One particular problem is that several printer setup files
(typically in a file called `/usr/share/texmf/dvips/config/config.pdf'
if you are using the `-Ppdf' switch) contain the `G' option for
`character shifting'.  This option will result in `fi' being rendered
as `#' (British Pounds sign) in several fonts, unless your version of
Dvips has a long-standing bug in its implementation fixed (only very
recent versions of Dvips have).

3 Emacs problems
****************

   * GNU Emacs versions prior to 21.1

     Don't use them.  20.x will not work, 21.0.x were prereleases,
     anyway.

   * Emacsen on Windows operating systems

     As of GNU Emacs 21.2, no image support is available in Emacs under
     Windows.  Without images, preview-latex is useless.  The current
     CVS version of Emacs available from
     `http://savannah.gnu.org/projects/emacs' now supports images
     including the PNG format, so Emacs 22 should work out of the box
     once it is released.  Another option for Windows users might be to
     try XEmacs.  preview-latex has successfully been installed with
     recent CVS versions of GNU Emacs, and both Cygwin XEmacs and the
     native Windows XEmacs.

     See the file `INSTALL.windows' for detailed installation
     instructions for this platform.

   * XEmacs

     There is are two larger problems known with older XEmacs releases.
     One leads to seriously mispositioned baselines and previews
     hanging far above other text on the same line.  This should be
     fixed as of XEmacs-21.4.9.

     The other core bug causes a huge delay when XEmacs's idea of the
     state of processes (like ghostscript) is wrong, and can lead to
     nasty spurious error messages.  It should be fixed in version
     21.4.8.

     Previews will only remain from one session to the next if you have
     version 1.81 or above of the `edit-utils' package, first released
     in the 2002-03-12 sumo tarball.

4 AUCTeX prior to 11.0
**********************

AUCTeX versions up to and including 10.0g have a bug in the calculation
of the offsets for the start of a region.  This affects `C-c C-r'
commands where the start of the region does not lie on the start of a
line.  It also affects regeneration of single previews.  To correct
this, apply the patch in `patches/auctex-10.patch'.  It might be more
prudent to install a more recent version of AUCTeX, however.

5 Too small bounding boxes
**************************

The bounding box of a preview is determined by the LaTeX package using
the pure TeX bounding boxes.  If there is material extending outside of
the TeX box, that material will be missing from the preview image. For
example this happens for the label-showing boxes from the `showkeys'
package (which has its own variant in preview-latex). Should this
happen to you, try setting `preview-fast-conversion' to `Off' (see the
manual).  The conversion will take slightly more time, but instead use
the bounding boxes from the EPS files generated by Dvips.

   Dvips generally does not miss things, but it does not understand
PostScript constructs like `\resizebox' or `\rotate' commands, so will
generate rather wrong boxes for those.  Dvips can be helped with the
`psfixbb' package option to preview (see the manual), which will tag
the corners of the included TeX box.  This will mostly be convenient
for _pure_ PostScript stuff like that created by PStricks, which Dvips
would otherwise reserve no space for.

6 x-symbol interoperation
*************************

Thanks to the work of Christoph Wedler, starting with version
`4.0h/beta' of x-symbol, the line parsing of AUCTeX and preview-latex
is fully supported.  Earlier versions exhibit problems.  However,
versions before 4.2.2 will cause a drastic slowdown of preview-latex's
parsing pass, so we don't recommend to use versions earlier than that.

   If you wonder what x-symbol is, it is a package that transforms
various tokens and subscripts to a more readable form while editing and
offers a few input methods handy especially for dealing with math. Take
a look at `http://x-symbol.sourceforge.net'.

   x-symbol versions up to 4.5.1-beta at least require an 8bit-clean
LaTeX implementation (with regard to error messages) for cooperation
with preview-latex.  Later versions may get along without it, like
preview-latex does now.

   If you experience problems with `circ.tex' in connection with both
x-symbol and Latin-1 characters, you may need to change your language
environment or, as a last resort, customize the variable
`LaTeX-command-style' by replacing the command `latex' with `latex
-translate-file=cp8bit'.

7 Middle-clicks paste instead of toggling
*****************************************

This is probably the fault of your favorite package.  `flyspell.el' and
`mouse-drag.el' are known to be affected in versions before Emacs 21.3.
Upgrade to the most recent version.

   `isearch.el' also shows this effect while searches are in progress,
but the code is such a complicated mess that no patch is in sight.
Better just end the search with `<RET>' before toggling and resume with
`C-s C-s' or similar afterwards.  Since previews over the current match
will auto-open, anyway, this should not be much of a problem in
practice.

