
\chapter{Introduction}

This document is an ''advanced user'' manual for Ion, the X11 window manager,
and version 3 specifically. It is an attempt attempt at documenting what is 
in Ion's configuration files, how to configure Ion by simple modifications 
to these files and how to write more complex extensions in Lua, the 
lightweight configuration and scripting language used by Ion. 

Readers unfamiliar with Lua is advised to first glance at the Lua manual at 

\centerurl{http://www.lua.org/docs.html}

and perhaps some tutorial pages at the lua-users wiki:

\centerurl{http://lua-users.org/wiki/LuaTutorial}

Back in this document, first in chapter \ref{chap:prelim} some key
concepts and relations are explained. These include the module system
and Ion's object and class hierarchies. While it might not at first 
occur that knowing such things would be necessary to \emph{configure} 
a program, this  material is essential because of the object-oriented 
nature of most of Ion's scripting interface.

The new user, fed up with the default key bindings and eager to just
quickly configure Ion to his liking may question the reasons for 
exposing the ''heavy'' internal OO structure in the scripting and
configuration interface. I'm not the one to  blame him for that. 
Sure it would be faster to configure Ion to everyone's liking
if a simpler binding configuration interface was provided. Such an
interface would, however, also be far more limited and make writing
extensions more complicated and the advantages from using a real 
scripting language would be partly lost. One more advantage from
a rich scripting and configuration interface is that it allows 
implementing scripts to read alternate configuration file formats,
ones that could be, for example, modified by external configuration tools. 

In chapter \ref{chap:config} the very basic Ion configuration know-how
is provided. All the different configuration files and their locations
are explained and instructions are given to allow the reader to
configure bindings and so-called ''winprops''. Chapter \ref{chap:gr}
explains the notion of drawing engines and graphical styles and how to
write new looks for Ion and more advanced aspects of Ion's scripting 
interface are documented in chapter \ref{chap:tricks} (a work in 
progress).

Finally, most of the functions provided by Ion's scripting interface
are listed and documented in the Function reference in chapter
\ref{sec:exports}. At the end of the document is an alphabetical
listing of all these functions.


