Don't obscure backtitle line

--- /usr/share/bsdconfig/dialog.subr.orig   2013-07-09 09:32:56.000000000 -0700
+++ /usr/share/bsdconfig/dialog.subr    2013-07-09 11:11:09.000000000 -0700
@@ -292,7 +292,31 @@ f_dialog_max_size()
        __max_size=$( stty size 2> /dev/null ) # usually "24 80"
        : ${__max_size:=$DEFAULT_TERMINAL_SIZE}
    fi
-   [ "$__var_height" ] && setvar "$__var_height" "${__max_size%%[$IFS]*}"
+   if [ "$__var_height" ]; then
+       local __height="${__max_size%%[$IFS]*}"
+       #
+       # If we're not using Xdialog(1), we should assume that $DIALOG
+       # will render --backtitle behind the widget. In such a case, we
+       # should prevent the widget from obscuring the backtitle (unless
+       # $NO_BACKTITLE is set and non-NULL, allowing a trap-door).
+       #
+       if [ ! "$USE_XDIALOG" ] && [ ! "$NO_BACKTITLE" ]; then
+           #
+           # If use_shadow (in ~/.dialogrc) is OFF, we need to
+           # subtract 4, otherwise 5. However, don't check this
+           # every time, rely on an initialization variable set
+           # by f_dialog_init().
+           #
+           local __adjust=5
+           [ "$NO_SHADOW" ] && __adjust=4
+
+           # Don't adjust the height if already too small (allowing
+           # obscured backtitle for small values of __height).
+           [ ${__height:-0} -gt 11 ] &&
+               __height=$(( $__height - $__adjust ))
+       fi
+       setvar "$__var_height" "$__height"
+   fi
    [ "$__var_width" ] && setvar "$__var_width" "${__max_size##*[$IFS]}"
 }

@@ -1999,6 +2023,12 @@ f_dialog_menutag2index_with_help()
 #                that (while running as root) sudo(8) authentication is
 #                required to proceed.
 #
+# Also reads ~/.dialogrc for the following information:
+#
+#  NO_SHADOW     Either NULL or Non-NULL. If use_shadow is OFF (case-
+#                insensitive) in ~/.dialogrc this is set to "1" (otherwise
+#                unset).
+#
 f_dialog_init()
 {
    DIALOG_SELF_INITIALIZE=
@@ -2058,6 +2088,22 @@ f_dialog_init()
    fi

    #
+   # Read ~/.dialogrc (unless using Xdialog(1)) for properties
+   #
+   if [ -f ~/.dialogrc ]; then
+       eval "$(
+           awk -v param=use_shadow -v expect=OFF \
+               -v set="NO_SHADOW=1" '
+           !/^[[:space:]]*(#|$)/ && \
+           tolower($1) ~ "^"param"(=|$)" && \
+           /[^#]*=/ {
+               sub(/^[^=]*=[[:space:]]*/, "")
+               if ( toupper($1) == expect ) print set";"
+           }' ~/.dialogrc
+       )"
+   fi
+
+   #
    # If we're already running as root but we got there by way of sudo(8)
    # and we have X11, we should merge the xauth(1) credentials from our
    # original user.