+# Allow, eg, x2 for width or height.
+if [ ! "${width#X}" = "$width" ]; then
+ width="${width/X/x}"
+ height=$width
+fi
+if [ ! "${width#x}" = "$width" ]; then
+ # Add a column for dividers.
+ width=${width#x}
+ width=$((width-1+(87*width)))
+fi
+if [ ! "${height#x}" = "$height" ]; then
+ height=${height#x}
+ height=$((24*height))
+ # Add a row for tmux.
+ [ $height -gt 1 ] && height=$((height+2))
+fi
+
+[ -n "$TMUX" ] && tmux_prefix="\033Ptmux;\033"
+echo -en "$tmux_prefix\033[8;$height;$width;t"