(*:wrap=hard:maxLineLen=78:*)

 theory JEdit

 imports Base

 begin

 chapter {* Introduction *}

 section {* Concepts and terminology *}

 text {* Isabelle/jEdit is a Prover IDE that integrates \emph{parallel

   proof checking} \cite{Wenzel:2009,Wenzel:2013:ITP} with

   \emph{asynchronous user interaction}

   \cite{Wenzel:2010,Wenzel:2012:UITP-EPTCS}, based on a

   document-oriented approach to \emph{continuous proof processing}

   \cite{Wenzel:2011:CICM,Wenzel:2012}. Many concepts and system

   components are fit together in order to make this work. The main

   building blocks are as follows.

   \begin{description}

   \item [PIDE] is a general framework for Prover IDEs based on

   Isabelle/Scala. It is built around a concept of parallel and

   asynchronous document processing, which is supported natively by the

   parallel proof engine that is implemented in Isabelle/ML. The prover

   discontinues the traditional TTY-based command loop, and supports

   direct editing of formal source text with rich formal markup for GUI

   rendering.

   \item [Isabelle/ML] is the implementation and extension language of

   Isabelle, see also \cite{isabelle-implementation}. It is integrated

   into the logical context of Isabelle/Isar and allows to manipulate

   logical entities directly. Arbitrary add-on tools may be implemented

   for object-logics such as Isabelle/HOL.

   \item [Isabelle/Scala] is the system programming language of

   Isabelle. It extends the pure logical environment of Isabelle/ML

   towards the ``real world'' of graphical user interfaces, text

   editors, IDE frameworks, web services etc.  Special infrastructure

   allows to transfer algebraic datatype values and formatted text

   easily between ML and Scala, using asynchronous protocol commands.

   \item [jEdit] is a sophisticated text editor implemented in

   Java.\footnote{\url{http://www.jedit.org}} It is easily extensible

   by plugins written in languages that work on the JVM, e.g.\

   Scala\footnote{\url{http://www.scala-lang.org/}}.

   \item [Isabelle/jEdit] is the main example application of the PIDE

   framework and the default user-interface for Isabelle. It targets

   both beginners and experts. Technically, Isabelle/jEdit combines a

   slightly modified version of the official jEdit code base with a

   special plugin for Isabelle, integrated as standalone application

   for the main operating system platforms: Linux, Windows, Mac OS X.

   \end{description}

   The subtle differences of Isabelle/ML versus Standard ML,

   Isabelle/Scala versus Scala, Isabelle/jEdit versus jEdit need to be

   taken into account when discussing any of these PIDE building blocks

   in public forums, mailing lists, or even scientific publications.

   *}

 section {* The Isabelle/jEdit Prover IDE *}

 text {*

   \begin{figure}[htbp]

   \begin{center}

   \includegraphics[width=\textwidth]{isabelle-jedit}

   \end{center}

   \caption{The Isabelle/jEdit Prover IDE}

   \end{figure}

   Isabelle/jEdit consists of some plugins for the well-known jEdit

   text editor \url{http://www.jedit.org}, according to the following

   principles.

   \begin{itemize}

   \item The original jEdit look-and-feel is generally preserved,

   although some default properties are changed to accommodate Isabelle

   (e.g.\ the text area font).

   \item Formal Isabelle/Isar text is checked asynchronously while

   editing.  The user is in full command of the editor, and the prover

   refrains from locking portions of the buffer.

   \item Prover feedback works via colors, boxes, squiggly underline,

   hyperlinks, popup windows, icons, clickable output --- all based on

   semantic markup produced by Isabelle in the background.

   \item Using the mouse together with the modifier key @{verbatim

   CONTROL} (Linux, Windows) or @{verbatim COMMAND} (Mac OS X) exposes

   additional formal content via tooltips and/or hyperlinks.

   \item Formal output (in popups etc.) may be explored recursively,

   using the same techniques as in the editor source buffer.

   \item Additional panels (e.g.\ \emph{Output}, \emph{Symbols}) are

   organized by the Dockable Window Manager of jEdit, which also allows

   multiple floating instances of each window class.

   \item The prover process and source files are managed on the editor

   side.  The prover operates on timeless and stateless document

   content as provided via Isabelle/Scala.

   \item Plugin options of jEdit (for the \emph{Isabelle} plugin) give

   access to a selection of Isabelle/Scala options and its persistent

   preferences, usually with immediate effect on the prover back-end or

   editor front-end.

   \item The logic image of the prover session may be specified within

   Isabelle/jEdit.  The new image is provided automatically by the

   Isabelle build tool after restart of the application.

   \end{itemize}

 *}

 subsection {* Documentation *}

 text {* Regular jEdit documentation is accessible via its @{verbatim

   Help} menu or @{verbatim F1} keyboard shortcut. This includes a full

   \emph{User's Guide} and \emph{Frequently Asked Questions} for this

   sophisticated text editor.

   Most of this information about jEdit is relevant for Isabelle/jEdit

   as well, but one needs to keep in mind that defaults sometimes

   differ, and the official jEdit documentation does not know about the

   Isabelle plugin with its special support for theory editing.

 *}

 subsection {* Plugins *}

 text {* The \emph{Plugin Manager} of jEdit allows to augment editor

   functionality by JVM modules (jars) that are provided by the central

   plugin repository, which is accessible by various mirror sites.

   Connecting to the plugin server infrastructure of the jEdit project

   allows to update bundled plugins or to add further functionality.

   This needs to be done with the usual care for such an open bazaar of

   contributions. Arbitrary combinations of add-on features are apt to

   cause problems.  It is advisable to start with the default

   configuration of Isabelle/jEdit and develop some understanding how

   it is supposed to work, before loading additional plugins at a grand

   scale.

   \medskip The main \emph{Isabelle} plugin is an integral part of

   Isabelle/jEdit and needs to remain active at all times! A few

   additional plugins are bundled with Isabelle/jEdit for convenience

   or out of necessity, notably \emph{Console} with its Isabelle/Scala

   sub-plugin and \emph{SideKick} with some Isabelle-specific parsers

   for document tree structure.  The \emph{ErrorList} plugin is

   required by \emph{SideKick}, but not used specifically in

   Isabelle/jEdit. *}

 subsection {* Options *}

 text {* Both jEdit and Isabelle have distinctive management of

   persistent options.

   Regular jEdit options are accessible via the dialogs for

   \emph{Global Options} and \emph{Plugin Options}.  Changed properties

   are stored eventually in @{verbatim

   "$ISABELLE_HOME_USER/jedit/properties"}.  In contrast, Isabelle

   system options are managed by Isabelle/Scala and changes stored in

   @{verbatim "$ISABELLE_HOME_USER/etc/preferences"}, independently of

   the jEdit properties.  See also \cite{isabelle-sys}, especially the

   coverage of sessions and command-line tools like @{tool build} or

   @{tool options}.

   Those Isabelle options that are declared as \textbf{public} are

   configurable in jEdit via \emph{Plugin Options / Isabelle /

   General}.  Moreover, there are various options for rendering of

   document content, which are configurable via \emph{Plugin Options /

   Isabelle / Rendering}.  Thus \emph{Plugin Options / Isabelle} in

   jEdit provides a view on certain Isabelle options.  Note that some

   of these options affect general parameters that are relevant outside

   Isabelle/jEdit as well, e.g.\ @{system_option threads} or

   @{system_option parallel_proofs} for the Isabelle build tool

   \cite{isabelle-sys}.

   \medskip All options are loaded on startup and saved on shutdown of

   Isabelle/jEdit.  Editing the machine-generated files @{verbatim

   "$ISABELLE_HOME_USER/jedit/properties"} or @{verbatim

   "$ISABELLE_HOME_USER/etc/preferences"} manually while the

   application is running is likely to cause surprise due to lost

   update!  *}

 subsection {* Keymaps *}

 text {* Keyboard shortcuts used to be managed as jEdit properties in

   the past, but recent versions (2013) have a separate concept of

   \emph{keymap} that is configurable via \emph{Global Options /

   Shortcuts}.  The @{verbatim imported} keymap is derived from the

   initial environment of properties that is available at the first

   start of the editor; afterwards the keymap file takes precedence.

   This is relevant for Isabelle/jEdit due to various fine-tuning of

   default properties, and additional keyboard shortcuts for Isabelle

   specific functionality. Users may change their keymap, but need to

   copy Isabelle-specific key bindings manually.  *}

 subsection {* Look-and-feel *}

 text {* jEdit is a Java/AWT/Swing application with some ambition to

   support ``native'' look-and-feel on all platforms, within the limits

   of what Oracle as Java provider and major operating system

   distributors allow (see also \secref{sec:problems}).

   Isabelle/jEdit enables platform-specific look-and-feel by default as

   follows:

   \begin{description}

   \item[Linux] The platform-independent \emph{Nimbus} is used by

   default, but the classic \emph{Metal} also works.  \emph{GTK+} works

   under the side-condition that the overall GTK theme is selected in a

   Swing-friendly way.\footnote{GTK support in Java/Swing was once

   marketed aggressively by Sun, but never quite finished, and is today

   (2013) lagging a bit behind further development of Swing and GTK.}

   \item[Windows] Regular \emph{Windows} is used by default, but

   platform-independent \emph{Nimbus} and \emph{Metal} also work.

   \item[Mac OS X] Regular \emph{Mac OS X} is used by default, but

   platform-independent \emph{Nimbus} and \emph{Metal} also work.

   Moreover the bundled \emph{MacOSX} plugin provides various functions

   that are expected from applications on that particular platform:

   quit from menu or dock, preferences menu, drag-and-drop of text

   files on the application, full-screen mode for main editor windows

   etc.

   \end{description}

   Users may experiment with different look-and-feels, but need to keep

   in mind that this extra variance of GUI functionality is unlikely to

   work in arbitrary combinations.  The historic \emph{CDE/Motif} is

   better avoided.  After changing the look-and-feel in \emph{Global

   Options / Appearance}, it is advisable to restart Isabelle/jEdit in

   order to take full effect.  *}

 chapter {* Prover IDE functionality *}

 section {* Text buffers and theories *}

 text {* As regular text editor, jEdit maintains a collection of open

   \emph{text buffers} to store source files; each buffer may be

   associated with any number of visible \emph{text areas}.  Buffers

   are subject to an \emph{edit mode} that is determined from the file

   type.  Files with extension \texttt{.thy} are assigned to the mode

   \emph{isabelle} and treated specifically.

   \medskip Isabelle theory files are automatically added to the formal

   document model of Isabelle/Scala, which maintains a family of

   versions of all sources for the prover.  The \emph{Theories} panel

   provides an overview of the status of continuous checking of theory

   sources.  Unlike batch sessions \cite{isabelle-sys}, theory nodes

   are identified by full path names; this allows to work with multiple

   (disjoint) Isabelle sessions simultaneously within the same editor

   session.

   Certain events to open or update buffers with theory files cause

   Isabelle/jEdit to resolve dependencies of \emph{theory imports}.

   The system requests to load additional files into editor buffers, in

   order to be included in the theory document model for further

   checking.  It is also possible to resolve dependencies

   automatically, depending on \emph{Plugin Options / Isabelle /

   General / Auto load} (Isabelle system option @{system_option

   jedit_auto_load}).

   \medskip The open text area views on theory buffers define the

   visible \emph{perspective} of Isabelle/jEdit.  This is taken as a

   hint for document processing: the prover ensures that those parts of

   a theory where the user is looking are checked, while other parts

   that are presently not required are ignored.  The perspective is

   changed by opening or closing text area windows, or scrolling within

   some window.

   The \emph{Theories} panel provides some further options to influence

   the process of continuous checking: it may be switched off globally

   to restrict the prover to superficial processing of command syntax.

   It is also possible to indicate theory nodes as \emph{required} for

   continuous checking: this means such nodes and all their imports are

   always processed independently of the visibility status (if

   continuous checking is enabled).  Big theory libraries that are

   marked as required can have significant impact on performance,

   though.

   \medskip Formal markup of checked theory content is turned into GUI

   rendering, based on a standard repertoire known from IDEs for

   programming languages: colors, icons, highlighting, squiggly

   underline, tooltips, hyperlinks etc.  For outer syntax of

   Isabelle/Isar there is some traditional syntax-highlighting via

   static keyword tables and tokenization within the editor.  In

   contrast, the painting of inner syntax (term language etc.)\ uses

   semantic information that is reported dynamically from the logical

   context.  Thus the prover can provide additional markup to help the

   user to understand the meaning of formal text, and to produce more

   text with some add-on tools (e.g.\ information messages by automated

   provers or disprovers running in the background).

   Such annotated text can be explored further by using the @{verbatim

   CONTROL} modifier key on Linux and Windows, or @{verbatim COMMAND}

   on Mac OS X.  Hovering with the mouse while the modifier is pressed

   reveals a \emph{tooltip} (grey box over the text with a yellow

   popup) and/or a \emph{hyperlink} (black rectangle over the text);

   see \figref{fig:tooltip}.

   \begin{figure}[htbp]

   \begin{center}

   \includegraphics[scale=0.3]{popup1}

   \end{center}

   \caption{Tooltip and hyperlink for some formal entity.}

   \label{fig:tooltip}

   \end{figure}

   Tooltip popups use the same rendering principles as the main text

   area, and further tooltips and/or hyperlinks may be exposed

   recursively by the same mechanism; see

   \figref{fig:nested-tooltips}.

   \begin{figure}[htbp]

   \begin{center}

   \includegraphics[scale=0.3]{popup2}

   \end{center}

   \caption{Nested tooltips over formal entities.}

   \label{fig:nested-tooltips}

   \end{figure}

   The tooltip popup window provides some controls to \emph{close} or

   \emph{detach} the window, turning it into a separate \emph{Info}

   dockable window managed by jEdit.  The @{verbatim ESCAPE} key closes

   \emph{all} popups, which is particularly relevant for nested

   tooltips stacking up. *}

 section {* Isabelle symbols and fonts *}

 text {* Isabelle sources consist of \emph{symbols} that extend plain

   ASCII to allow infinitely many mathematical symbols within the

   formal sources.  This works without depending on particular

   encodings or varying Unicode standards \cite{Wenzel:2011:CICM}.

   For the prover back-end, formal text consists of ASCII characters

   that are grouped according to some simple rules, e.g.\ as plain

   ``@{verbatim a}'' or symbolic ``@{verbatim "\<alpha>"}''.

   For the editor front-end, a certain subset of symbols is rendered as

   Unicode glyphs, in order to show ``@{verbatim "\<alpha>"}'' as ``@{text

   "\<alpha>"}'', for example.  This symbol interpretation is specified by the

   Isabelle system distribution (@{file "$ISABELLE_HOME/etc/symbols"})

   or by the user (@{verbatim "$ISABELLE_HOME_USER/etc/symbols"}).

   The appendix of \cite{isabelle-isar-ref} gives an overview of the

   standard interpretation of finitely many symbols from the infinite

   collection.  Uninterpreted symbols are shown literally, e.g.\

   ``@{verbatim "\<foobar>"}''.

   \medskip Technically, the Unicode view on Isabelle symbols is an

   \emph{encoding} in Isabelle/jEdit, which is called @{verbatim

   "UTF-8-Isabelle"} and enabled by default.  Sometimes such defaults

   are reset accidentally, or malformed UTF-8 sequences in the text

   force jEdit to fall back on a different encoding like @{verbatim

   "ISO-8859-15"}.  In that case, verbatim ``@{verbatim "\<alpha>"}'' will be

   shown in the text buffer instead of its Unicode rendering ``@{text

   "\<alpha>"}''.  The jEdit menu operation \emph{File / Reload with Encoding

   / UTF-8-Isabelle} helps to resolve such problems, potentially after

   repairing malformed parts of the text.

   \medskip Correct rendering via Unicode requires a font that contains

   glyphs for the corresponding codepoints.  Most system fonts lack

   that, so Isabelle/jEdit prefers its own application font @{verbatim

   IsabelleText}, which ensures that standard collection of Isabelle

   symbols are actually seen on the screen (or printer).

   Note that a Java/AWT/Swing application can load additional fonts

   only if they are not installed as system font already!  This means

   some old version of @{verbatim IsabelleText} that happens to be

   already present prevents Isabelle/jEdit from using its current

   bundled version.  This might result in missing glyphs (black

   rectangles), since obsolete versions of @{verbatim IsabelleText}

   lack recent improvements of Unicode glyph coverage.  This problem

   can be avoided by refraining to ``install'' any version of

   @{verbatim IsabelleText} in the first place.

   \medskip \paragraph{Input methods.} In principle, Isabelle/jEdit

   could delegate the problem to produce Isabelle symbols in their

   Unicode rendering to the underlying operating system and its

   \emph{input methods}.  Regular jEdit also provides various ways to

   work with \emph{abbreviations} to produce certain non-ASCII

   characters.  Since none of these standard input methods work

   satisfactorily for the mathematical characters required for

   Isabelle, various specific Isabelle/jEdit mechanisms are provided.

   Here is a summary for practically relevant input methods for

   Isabelle symbols:

   \begin{enumerate}

   \item The \emph{Symbols} panel with some GUI buttons to insert

   certain symbols in the text buffer.  There are also tooltips to

   reveal to official Isabelle representation with some additional

   information about \emph{symbol abbreviations} (see below).

   \item Copy / paste from decoded source files: text that is rendered

   as Unicode already can be re-used to produce further such text.

   This also works between different applications, e.g.\ Isabelle/jEdit

   and some web browser or mail client, as long as the same Unicode

   view on Isabelle symbols is used uniformly.

   \item Copy / paste from prover output within Isabelle/jEdit.  The

   same principles as for text buffers apply, but note that \emph{copy}

   in Isabelle \emph{Output} works via the keyboard shortcut @{verbatim

   "C+c"}, not jEdit menu actions.

   \item Completion provided by Isabelle plugin (see

   \secref{sec:completion}).  Isabelle symbols have a canonical name

   and optional abbreviations.  This can be used with the text

   completion mechanism of Isabelle/jEdit, to replace a prefix of the

   actual symbol like @{verbatim "\<lambda>"}, or its backslashed name

   @{verbatim "\\"}@{verbatim "lambda"}, or its ASCII abbreviation

   @{verbatim "%"} by the Unicode rendering.

   The following table is an extract of the information provided by the

   standard @{file "$ISABELLE_HOME/etc/symbols"} file:

   \medskip

   \begin{tabular}{lll}

     \textbf{symbol} & \textbf{abbreviation} & \textbf{backslashed name} \\\hline

     @{text "\<lambda>"}   & @{verbatim "%"}     &  @{verbatim "\\lambda"}         \\

     @{text "\<Rightarrow>"}  & @{verbatim "=>"}    &  @{verbatim "\\Rightarrow"}     \\

     @{text "\<Longrightarrow>"} & @{verbatim "==>"}   &  @{verbatim "\\Longrightarrow"} \\

     @{text "\<And>"}  & @{verbatim "!!"}    &  @{verbatim "\\And"}            \\

     @{text "\<equiv>"}  & @{verbatim "=="}    &  @{verbatim "\\equiv"}          \\

     @{text "\<forall>"}   & @{verbatim "!"}     &  @{verbatim "\\forall"}         \\

     @{text "\<exists>"}   & @{verbatim "?"}     &  @{verbatim "\\exists"}         \\

     @{text "\<longrightarrow>"} & @{verbatim "-->"}   &  @{verbatim "\\longrightarrow"} \\

     @{text "\<and>"}   & @{verbatim "&"}     &  @{verbatim "\\and"}            \\

     @{text "\<or>"}   & @{verbatim "|"}     &  @{verbatim "\\or"}             \\

     @{text "\<not>"}   & @{verbatim "~"}     &  @{verbatim "\\not"}            \\

     @{text "\<noteq>"}   & @{verbatim "~="}    &  @{verbatim "\\noteq"}          \\

     @{text "\<in>"}   & @{verbatim ":"}     &  @{verbatim "\\in"}             \\

     @{text "\<notin>"}   & @{verbatim "~:"}    &  @{verbatim "\\notin"}          \\

   \end{tabular}

   \medskip

   Note that the above abbreviations refer to the input method. The

   logical notation provides ASCII alternatives that often coincide,

   but deviate occasionally.  Writing formal sources directly with

   ASCII replacement notation like @{verbatim "!"} or @{verbatim "ALL"}

   is considered old-fashioned in 2013!

   \end{enumerate}

   Raw Unicode characters within prover source files should be

   restricted to informal parts, e.g.\ to write text in non-latin

   alphabets.  Mathematical symbols should be defined via the official

   rendering tables, to avoid problems with portability and long-term

   storage of formal text.

   \paragraph{Control symbols.} There are some special control symbols

   to modify the style of a single symbol (without nesting). Control

   symbols may be applied to a region of selected text, either using

   the \emph{Symbols} panel or keyboard shortcuts; these editor

   operations produce a separate control symbol for each symbol in the

   text, in order to make the whole text appear in a certain style.

   \medskip

   \begin{tabular}{lll}

     \textbf{symbol}      & style       & keyboard shortcut \\\hline

     @{verbatim "\<^sup>"} & superscript & @{verbatim "C+e UP"} \\

     @{verbatim "\<^sub>"} & subscript   & @{verbatim "C+e DOWN"} \\

     @{verbatim "\<^bold>"} & bold face  & @{verbatim "C+e RIGHT"} \\

                           & reset      & @{verbatim "C+e LEFT"} \\

   \end{tabular}

   It is also possible to complete on @{verbatim "\\"}@{verbatim sup},

   @{verbatim "\\"}@{verbatim sub}, @{verbatim "\\"}@{verbatim bold} as

   for regular symbols.

 *}

 section {* Text completion \label{sec:completion} *}

 text {*

   Text completion works via some light-weight GUI popup, which is triggered by

   keyboard events during the normal editing process in the main jEdit text

   area and a few additional text fields. The popup interprets special keys:

   @{verbatim TAB}, @{verbatim ESCAPE}, @{verbatim UP}, @{verbatim DOWN},

   @{verbatim PAGE_UP}, @{verbatim PAGE_DOWN}. All other key events are passed

   to the jEdit text area --- this allows to ignore unwanted completions most

   of the time and continue typing quickly.

   Various Isabelle plugin options control the popup behavior and immediate

   insertion into buffer.

   Isabelle Symbols are completed in backslashed forms, e.g.\ @{verbatim

   "\\"}@{verbatim "forall"} or @{verbatim "\<forall>"} that both produce the Isabelle

   symbol @{text "\<forall>"} in its Unicode rendering. Alternatively, symbol

   abbreviations may be used as specified in @{file

   "$ISABELLE_HOME/etc/symbols"}.

   \emph{Explicit completion} works via standard jEdit shortcut @{verbatim

   "C+b"}, which is remapped to action @{verbatim "isabelle.complete"}, with a

   fall-back on regular @{verbatim "complete-word"} for non-Isabelle buffers.

   \emph{Implicit completion} works via keyboard input on text area, with popup

   or immediate insertion into buffer. Plain words require at least 3

   characters to be completed.

   \emph{Immediate completion} means the (unique) replacement text is inserted

   into the buffer without popup. This mode ignores plain words and requires

   more than one characters for symbol abbreviations. Otherwise it falls back

   on completion popup.

 *}

 chapter {* Known problems and workarounds \label{sec:problems} *}

 text {*

   \begin{itemize}

   \item \textbf{Problem:} Lack of dependency management for auxiliary files

   that contribute to a theory (e.g.\ @{command ML_file}).

   \textbf{Workaround:} Re-load files manually within the prover, by

   editing corresponding command in the text.

   \item \textbf{Problem:} Odd behavior of some diagnostic commands with

   global side-effects, like writing a physical file.

   \textbf{Workaround:} Avoid such commands.

   \item \textbf{Problem:} No way to delete document nodes from the overall

   collection of theories.

   \textbf{Workaround:} Ignore unused files.  Restart whole

   Isabelle/jEdit session in worst-case situation.

   \item \textbf{Problem:} Keyboard shortcuts @{verbatim "C+PLUS"} and

   @{verbatim "C+MINUS"} for adjusting the editor font size depend on

   platform details and national keyboards.

   \textbf{Workaround:} Use numeric keypad or rebind keys in the

   jEdit Shortcuts options dialog.

   \item \textbf{Problem:} The Mac OS X keyboard shortcut @{verbatim

   "COMMAND+COMMA"} for application \emph{Preferences} is in conflict

   with the jEdit default shortcut for \emph{Incremental Search Bar}

   (action @{verbatim "quick-search"}).

   \textbf{Workaround:} Remap in jEdit manually according to national

   keyboard, e.g.\ @{verbatim "COMMAND+SLASH"} on English ones.

   \item \textbf{Problem:} Mac OS X system fonts sometimes lead to

   character drop-outs in the main text area.

   \textbf{Workaround:} Use the default @{verbatim IsabelleText} font.

   (Do not install that font on the system.)

   \item \textbf{Problem:} Some Linux / X11 input methods such as IBus

   tend to disrupt key event handling of Java/AWT/Swing.

   \textbf{Workaround:} Do not use input methods, reset the environment

   variable @{verbatim XMODIFIERS} within Isabelle settings (default in

   Isabelle2013-1).

   \item \textbf{Problem:} Some Linux / X11 window managers that are

   not ``re-parenting'' cause problems with additional windows opened

   by Java. This affects either historic or neo-minimalistic window

   managers like @{verbatim awesome} or @{verbatim xmonad}.

   \textbf{Workaround:} Use regular re-parenting window manager.

   \item \textbf{Problem:} Recent forks of Linux / X11 window managers

   and desktop environments (variants of Gnome) disrupt the handling of

   menu popups and mouse positions of Java/AWT/Swing.

   \textbf{Workaround:} Use mainstream versions of Linux desktops.

   \item \textbf{Problem:} Full-screen mode via jEdit action @{verbatim

   "toggle-full-screen"} (default shortcut @{verbatim F11}) works on

   Windows, but not on Mac OS X or various Linux / X11 window managers.

   \textbf{Workaround:} Use native full-screen control of the window

   manager, if available (notably on Mac OS X).

   \item \textbf{Problem:} Full-screen mode and dockable windows in

   \emph{floating} state may lead to confusion about window placement

   (depending on platform characteristics).

   \textbf{Workaround:} Avoid this combination.

   \end{itemize}

 *}

 end