Add viewports to the manual.  Adapted from FS#9934 by Jonas Häggqvist and FS#10553 by David Kauffmann


git-svn-id: svn://svn.rockbox.org/rockbox/trunk@22756 a1c6a512-1295-4272-9138-f99709370657
diff --git a/manual/advanced_topics/viewports/grayscale-vp-syntax.tex b/manual/advanced_topics/viewports/grayscale-vp-syntax.tex
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+\subsubsection{Viewport Declaration Syntax}
+
+{\config{\%V}}{\textbar}x{\textbar}y{\textbar}[width]{\textbar}[height]{\textbar}[font]{\textbar}[fgshade]{\textbar}[bgshade]{\textbar}%
+
+    \begin{itemize}
+      \item 'fgshade' and bgshade are numbers in the range '0' (= black) to '3'
+      (= white).
+      \item 'font' is a number - '0' is the built-in system font, '1' is the
+      user-selected font.
+      \item Only the coordinates \emph{have} to be specified. Leaving the other
+      definitions blank will set them to their default values.
+      \note{The correct number of {\textbar}s with hyphens in blank fields
+      are still needed in any case.}
+    \end{itemize}
+
+\begin{example}
+    %V|12|20|-|-|1|-|-|
+    %sThis viewport is displayed permanently. It starts 12px from the left and
+    %s20px from the top of the screen, and fills the rest of the screen from
+    %sthat point. The lines will scroll if this text does not fit in the viewport.
+    %sThe user font is used, as are the default foreground/background shades.
+\end{example}
+\begin{rbtabular}{.75\textwidth}{XX}{Viewport definition & Default value}{}{}
+  width/height & remaining part of screen \\
+  font & user defined \\
+  shade & black foreground on white background \\
+\end{rbtabular}