+ /*
+ * COL_BACKGROUND is what we use as the normal background colour.
+ * Unusually, though, it isn't colour #0: COL_SYSBACKGROUND, a bit
+ * darker, takes that place. This means that if the user resizes
+ * an Untangle window so as to change its aspect ratio, the
+ * still-square playable area will be distinguished from the dead
+ * space around it.
+ */
+ game_mkhighlight(fe, ret, COL_BACKGROUND, -1, COL_SYSBACKGROUND);