Use the \note and \warning macros where appropriate.
diff --git a/Doc/lib/libgl.tex b/Doc/lib/libgl.tex
index cf51651..ecf4c36 100644
--- a/Doc/lib/libgl.tex
+++ b/Doc/lib/libgl.tex
@@ -10,11 +10,10 @@
\emph{Graphics Library}.
It is available only on Silicon Graphics machines.
-\strong{Warning:}
-Some illegal calls to the GL library cause the Python interpreter to dump
-core.
+\warning{Some illegal calls to the GL library cause the Python
+interpreter to dump core.
In particular, the use of most GL calls is unsafe before the first
-window is opened.
+window is opened.}
The module is too large to document here in its entirety, but the
following should help you to get started.