Give the Help viewer a font-size button. This isn't documented by MS,

but is documented by others on the web, and the defn of the magic flag
needed appears in MS's htmlhelp.h header file.

Doc/tools/prechm.py

@@ -36,6 +36,35 @@ Usage: make_chm.py [-c] [-k] [-p] [-v 1.5[.x]] filename
 # the 2.2 in Python 2.2).
 # The magical numbers in the long line under [WINDOWS] set most of the
 # user-visible features (visible buttons, tabs, etc).
+# About 0x10384e:  This defines the buttons in the help viewer.  The
+# following defns are taken from htmlhelp.h.  Not all possibilities
+# actually work, and not all those that work are available from the Help
+# Workshop GUI.  In particular, the Zoom/Font button works and is not
+# available from the GUI.  The ones we're using are marked with 'x':
+#
+#    0x000002   Hide/Show   x
+#    0x000004   Back        x
+#    0x000008   Forward     x
+#    0x000010   Stop
+#    0x000020   Refresh
+#    0x000040   Home        x
+#    0x000080   Forward
+#    0x000100   Back
+#    0x000200   Notes
+#    0x000400   Contents
+#    0x000800   Locate      x
+#    0x001000   Options     x
+#    0x002000   Print       x
+#    0x004000   Index
+#    0x008000   Search
+#    0x010000   History
+#    0x020000   Favorites
+#    0x040000   Jump 1
+#    0x080000   Jump 2
+#    0x100000   Zoom/Font   x
+#    0x200000   TOC Next
+#    0x400000   TOC Prev
+
 project_template = '''
 [OPTIONS]
 Compiled file=%(arch)s.chm
@@ -51,7 +80,7 @@ Title=Python %(version)s Documentation
 
 [WINDOWS]
 %(arch)s="Python %(version)s Documentation","%(arch)s.hhc","%(arch)s.hhk",\
-"index.html","index.html",,,,,0x63520,220,0x384e,[271,372,740,718],,,,,,,0
+"index.html","index.html",,,,,0x63520,220,0x10384e,[271,372,740,718],,,,,,,0
 
 [FILES]
 '''