diff --git a/cube.c b/cube.c
index cf5e512..6a867a4 100644
--- a/cube.c
+++ b/cube.c
@@ -1568,9 +1568,9 @@ static void game_redraw(frontend *fe, game_drawstate *ds, game_state *oldstate,
 			     + ds->oy);
         }
 
-        draw_polygon(fe, coords, state->squares[i].npoints, TRUE,
-                     state->squares[i].blue ? COL_BLUE : COL_BACKGROUND);
-        draw_polygon(fe, coords, state->squares[i].npoints, FALSE, COL_BORDER);
+        draw_polygon(fe, coords, state->squares[i].npoints,
+                     state->squares[i].blue ? COL_BLUE : COL_BACKGROUND,
+		     COL_BORDER);
     }
 
     /*
@@ -1650,9 +1650,9 @@ static void game_redraw(frontend *fe, game_drawstate *ds, game_state *oldstate,
                 continue;
         }
 
-        draw_polygon(fe, coords, poly->order, TRUE,
-                     state->facecolours[i] ? COL_BLUE : COL_BACKGROUND);
-        draw_polygon(fe, coords, poly->order, FALSE, COL_BORDER);
+        draw_polygon(fe, coords, poly->order,
+                     state->facecolours[i] ? COL_BLUE : COL_BACKGROUND,
+		     COL_BORDER);
     }
     sfree(poly);
 
diff --git a/fifteen.c b/fifteen.c
index bd791ea..6f75514 100644
--- a/fifteen.c
+++ b/fifteen.c
@@ -654,13 +654,11 @@ static void draw_tile(frontend *fe, game_drawstate *ds, game_state *state,
         coords[3] = y;
         coords[4] = x;
         coords[5] = y + TILE_SIZE - 1;
-        draw_polygon(fe, coords, 3, TRUE, COL_LOWLIGHT);
-        draw_polygon(fe, coords, 3, FALSE, COL_LOWLIGHT);
+        draw_polygon(fe, coords, 3, COL_LOWLIGHT, COL_LOWLIGHT);
 
         coords[0] = x;
         coords[1] = y;
-        draw_polygon(fe, coords, 3, TRUE, COL_HIGHLIGHT);
-        draw_polygon(fe, coords, 3, FALSE, COL_HIGHLIGHT);
+        draw_polygon(fe, coords, 3, COL_HIGHLIGHT, COL_HIGHLIGHT);
 
         draw_rect(fe, x + HIGHLIGHT_WIDTH, y + HIGHLIGHT_WIDTH,
                   TILE_SIZE - 2*HIGHLIGHT_WIDTH, TILE_SIZE - 2*HIGHLIGHT_WIDTH,
@@ -709,13 +707,11 @@ static void game_redraw(frontend *fe, game_drawstate *ds, game_state *oldstate,
         coords[9] = COORD(state->h) + HIGHLIGHT_WIDTH - 1;
         coords[6] = coords[8] + TILE_SIZE;
         coords[7] = coords[9] - TILE_SIZE;
-        draw_polygon(fe, coords, 5, TRUE, COL_HIGHLIGHT);
-        draw_polygon(fe, coords, 5, FALSE, COL_HIGHLIGHT);
+        draw_polygon(fe, coords, 5, COL_HIGHLIGHT, COL_HIGHLIGHT);
 
         coords[1] = COORD(0) - HIGHLIGHT_WIDTH;
         coords[0] = COORD(0) - HIGHLIGHT_WIDTH;
-        draw_polygon(fe, coords, 5, TRUE, COL_LOWLIGHT);
-        draw_polygon(fe, coords, 5, FALSE, COL_LOWLIGHT);
+        draw_polygon(fe, coords, 5, COL_LOWLIGHT, COL_LOWLIGHT);
 
         ds->started = TRUE;
     }
diff --git a/flip.c b/flip.c
index 9ad3eb2..1d7c4f5 100644
--- a/flip.c
+++ b/flip.c
@@ -1059,8 +1059,7 @@ static void draw_tile(frontend *fe, game_drawstate *ds,
 	if (animtime < 0.5)
 	    colour = COL_WRONG + COL_RIGHT - colour;
 
-	draw_polygon(fe, coords, 4, TRUE, colour);
-	draw_polygon(fe, coords, 4, FALSE, COL_GRID);
+	draw_polygon(fe, coords, 4, colour, COL_GRID);
     }
 
     /*
diff --git a/gtk.c b/gtk.c
index ef795a4..1a79f0e 100644
--- a/gtk.c
+++ b/gtk.c
@@ -348,7 +348,7 @@ void draw_line(frontend *fe, int x1, int y1, int x2, int y2, int colour)
 }
 
 void draw_polygon(frontend *fe, int *coords, int npoints,
-                  int fill, int colour)
+                  int fillcolour, int outlinecolour)
 {
     GdkPoint *points = snewn(npoints, GdkPoint);
     int i;
@@ -358,19 +358,32 @@ void draw_polygon(frontend *fe, int *coords, int npoints,
         points[i].y = coords[i*2+1];
     }
 
-    gdk_gc_set_foreground(fe->gc, &fe->colours[colour]);
-    gdk_draw_polygon(fe->pixmap, fe->gc, fill, points, npoints);
+    if (fillcolour >= 0) {
+	gdk_gc_set_foreground(fe->gc, &fe->colours[fillcolour]);
+	gdk_draw_polygon(fe->pixmap, fe->gc, TRUE, points, npoints);
+    }
+    assert(outlinecolour >= 0);
+    gdk_gc_set_foreground(fe->gc, &fe->colours[outlinecolour]);
+    gdk_draw_polygon(fe->pixmap, fe->gc, FALSE, points, npoints);
 
     sfree(points);
 }
 
 void draw_circle(frontend *fe, int cx, int cy, int radius,
-                 int fill, int colour)
+                 int fillcolour, int outlinecolour)
 {
-    gdk_gc_set_foreground(fe->gc, &fe->colours[colour]);
-    gdk_draw_arc(fe->pixmap, fe->gc, fill,
-                 cx - radius, cy - radius,
-                 2 * radius, 2 * radius, 0, 360 * 64);
+    if (fillcolour >= 0) {
+	gdk_gc_set_foreground(fe->gc, &fe->colours[fillcolour]);
+	gdk_draw_arc(fe->pixmap, fe->gc, TRUE,
+		     cx - radius, cy - radius,
+		     2 * radius, 2 * radius, 0, 360 * 64);
+    }
+
+    assert(outlinecolour >= 0);
+    gdk_gc_set_foreground(fe->gc, &fe->colours[outlinecolour]);
+    gdk_draw_arc(fe->pixmap, fe->gc, FALSE,
+		 cx - radius, cy - radius,
+		 2 * radius, 2 * radius, 0, 360 * 64);
 }
 
 struct blitter {
diff --git a/guess.c b/guess.c
index 12d8b1b..9b94123 100644
--- a/guess.c
+++ b/guess.c
@@ -1021,8 +1021,8 @@ static void draw_peg(frontend *fe, game_drawstate *ds, int cx, int cy,
         draw_rect(fe, cx-CGAP, cy-CGAP, PEGSZ+CGAP*2, PEGSZ+CGAP*2,
                   COL_BACKGROUND);
     if (PEGRAD > 0) {
-        draw_circle(fe, cx+PEGRAD, cy+PEGRAD, PEGRAD, 1, COL_EMPTY + col);
-        draw_circle(fe, cx+PEGRAD, cy+PEGRAD, PEGRAD, 0, COL_EMPTY + col);
+        draw_circle(fe, cx+PEGRAD, cy+PEGRAD, PEGRAD,
+		    COL_EMPTY + col, COL_EMPTY + col);
     } else
         draw_rect(fe, cx, cy, PEGSZ, PEGSZ, COL_EMPTY + col);
     draw_update(fe, cx-CGAP, cy-CGAP, PEGSZ+CGAP*2, PEGSZ+CGAP*2);
@@ -1030,7 +1030,7 @@ static void draw_peg(frontend *fe, game_drawstate *ds, int cx, int cy,
 
 static void draw_cursor(frontend *fe, game_drawstate *ds, int x, int y)
 {
-    draw_circle(fe, x+PEGRAD, y+PEGRAD, PEGRAD+CGAP, 0, COL_CURSOR);
+    draw_circle(fe, x+PEGRAD, y+PEGRAD, PEGRAD+CGAP, -1, COL_CURSOR);
 
     draw_update(fe, x-CGAP, y-CGAP, PEGSZ+CGAP*2, PEGSZ+CGAP*2);
 }
@@ -1129,8 +1129,7 @@ static void hint_redraw(frontend *fe, game_drawstate *ds, int guess,
                 rowy += HINTOFF;
             }
             if (HINTRAD > 0) {
-                draw_circle(fe, rowx+HINTRAD, rowy+HINTRAD, HINTRAD, 1, col);
-                draw_circle(fe, rowx+HINTRAD, rowy+HINTRAD, HINTRAD, 0, col);
+                draw_circle(fe, rowx+HINTRAD, rowy+HINTRAD, HINTRAD, col, col);
             } else {
                 draw_rect(fe, rowx, rowy, HINTSZ, HINTSZ, col);
             }
diff --git a/mines.c b/mines.c
index 6cfb634..7597d07 100644
--- a/mines.c
+++ b/mines.c
@@ -2751,13 +2751,12 @@ static void draw_tile(frontend *fe, game_drawstate *ds,
 	    coords[3] = y;
 	    coords[4] = x;
 	    coords[5] = y + TILE_SIZE - 1;
-	    draw_polygon(fe, coords, 3, TRUE, COL_LOWLIGHT ^ hl);
-	    draw_polygon(fe, coords, 3, FALSE, COL_LOWLIGHT ^ hl);
+	    draw_polygon(fe, coords, 3, COL_LOWLIGHT ^ hl, COL_LOWLIGHT ^ hl);
 
 	    coords[0] = x;
 	    coords[1] = y;
-	    draw_polygon(fe, coords, 3, TRUE, COL_HIGHLIGHT ^ hl);
-	    draw_polygon(fe, coords, 3, FALSE, COL_HIGHLIGHT ^ hl);
+	    draw_polygon(fe, coords, 3, COL_HIGHLIGHT ^ hl,
+			 COL_HIGHLIGHT ^ hl);
 
 	    draw_rect(fe, x + HIGHLIGHT_WIDTH, y + HIGHLIGHT_WIDTH,
 		      TILE_SIZE - 2*HIGHLIGHT_WIDTH, TILE_SIZE - 2*HIGHLIGHT_WIDTH,
@@ -2778,14 +2777,12 @@ static void draw_tile(frontend *fe, game_drawstate *ds,
 	    SETCOORD(3, 0.25, 0.8);
 	    SETCOORD(4, 0.55, 0.7);
 	    SETCOORD(5, 0.55, 0.35);
-	    draw_polygon(fe, coords, 6, TRUE, COL_FLAGBASE);
-	    draw_polygon(fe, coords, 6, FALSE, COL_FLAGBASE);
+	    draw_polygon(fe, coords, 6, COL_FLAGBASE, COL_FLAGBASE);
 
 	    SETCOORD(0, 0.6, 0.2);
 	    SETCOORD(1, 0.6, 0.5);
 	    SETCOORD(2, 0.2, 0.35);
-	    draw_polygon(fe, coords, 3, TRUE, COL_FLAG);
-	    draw_polygon(fe, coords, 3, FALSE, COL_FLAG);
+	    draw_polygon(fe, coords, 3, COL_FLAG, COL_FLAG);
 #undef SETCOORD
 
 	} else if (v == -3) {
@@ -2863,8 +2860,7 @@ static void draw_tile(frontend *fe, game_drawstate *ds,
 		    xdy = -tdy;
 		}
 
-		draw_polygon(fe, coords, 5*4, TRUE, COL_MINE);
-		draw_polygon(fe, coords, 5*4, FALSE, COL_MINE);
+		draw_polygon(fe, coords, 5*4, COL_MINE, COL_MINE);
 
 		draw_rect(fe, cx-r/3, cy-r/3, r/3, r/4, COL_HIGHLIGHT);
 	    }
@@ -2929,13 +2925,11 @@ static void game_redraw(frontend *fe, game_drawstate *ds, game_state *oldstate,
         coords[9] = COORD(state->h) + OUTER_HIGHLIGHT_WIDTH - 1;
         coords[6] = coords[8] + TILE_SIZE;
         coords[7] = coords[9] - TILE_SIZE;
-        draw_polygon(fe, coords, 5, TRUE, COL_HIGHLIGHT);
-        draw_polygon(fe, coords, 5, FALSE, COL_HIGHLIGHT);
+        draw_polygon(fe, coords, 5, COL_HIGHLIGHT, COL_HIGHLIGHT);
 
         coords[1] = COORD(0) - OUTER_HIGHLIGHT_WIDTH;
         coords[0] = COORD(0) - OUTER_HIGHLIGHT_WIDTH;
-        draw_polygon(fe, coords, 5, TRUE, COL_LOWLIGHT);
-        draw_polygon(fe, coords, 5, FALSE, COL_LOWLIGHT);
+        draw_polygon(fe, coords, 5, COL_LOWLIGHT, COL_LOWLIGHT);
 
         ds->started = TRUE;
     }
@@ -3091,7 +3085,7 @@ void draw_text(frontend *fe, int x, int y, int fonttype, int fontsize,
 void draw_rect(frontend *fe, int x, int y, int w, int h, int colour) {}
 void draw_line(frontend *fe, int x1, int y1, int x2, int y2, int colour) {}
 void draw_polygon(frontend *fe, int *coords, int npoints,
-                  int fill, int colour) {}
+                  int fillcolour, int outlinecolour) {}
 void clip(frontend *fe, int x, int y, int w, int h) {}
 void unclip(frontend *fe) {}
 void start_draw(frontend *fe) {}
diff --git a/net.c b/net.c
index 767ef31..2e86700 100644
--- a/net.c
+++ b/net.c
@@ -2405,8 +2405,7 @@ static void draw_tile(frontend *fe, game_state *state, game_drawstate *ds,
             points[i+1] = by+(int)(cy+ty);
         }
 
-        draw_polygon(fe, points, 4, TRUE, col);
-        draw_polygon(fe, points, 4, FALSE, COL_WIRE);
+        draw_polygon(fe, points, 4, col, COL_WIRE);
     }
 
     /*
diff --git a/netslide.c b/netslide.c
index 236491a..fe77794 100644
--- a/netslide.c
+++ b/netslide.c
@@ -1436,8 +1436,7 @@ static void draw_tile(frontend *fe, game_drawstate *ds, game_state *state,
             points[i+1] = by+(int)(cy+ey);
         }
 
-        draw_polygon(fe, points, 4, TRUE, col);
-        draw_polygon(fe, points, 4, FALSE, COL_WIRE);
+        draw_polygon(fe, points, 4, col, COL_WIRE);
     }
 
     /*
@@ -1533,8 +1532,7 @@ static void draw_arrow(frontend *fe, game_drawstate *ds,
     POINT(5, 3 * TILE_SIZE / 8, TILE_SIZE / 2);   /* left concave */
     POINT(6,     TILE_SIZE / 4, TILE_SIZE / 2);   /* left corner */
 
-    draw_polygon(fe, coords, 7, TRUE, COL_LOWLIGHT);
-    draw_polygon(fe, coords, 7, FALSE, COL_TEXT);
+    draw_polygon(fe, coords, 7, COL_LOWLIGHT, COL_TEXT);
 }
 
 static void game_redraw(frontend *fe, game_drawstate *ds, game_state *oldstate,
diff --git a/osx.m b/osx.m
index b009cd7..c3f6d1b 100644
--- a/osx.m
+++ b/osx.m
@@ -1216,16 +1216,13 @@ struct frontend {
  * Drawing routines called by the midend.
  */
 void draw_polygon(frontend *fe, int *coords, int npoints,
-                  int fill, int colour)
+                  int fillcolour, int outlinecolour)
 {
     NSBezierPath *path = [NSBezierPath bezierPath];
     int i;
 
     [[NSGraphicsContext currentContext] setShouldAntialias:YES];
 
-    assert(colour >= 0 && colour < fe->ncolours);
-    [fe->colours[colour] set];
-
     for (i = 0; i < npoints; i++) {
 	NSPoint p = { coords[i*2] + 0.5, coords[i*2+1] + 0.5 };
 	if (i == 0)
@@ -1236,30 +1233,37 @@ void draw_polygon(frontend *fe, int *coords, int npoints,
 
     [path closePath];
 
-    if (fill)
+    if (fillcolour >= 0) {
+	assert(fillcolour >= 0 && fillcolour < fe->ncolours);
+	[fe->colours[fillcolour] set];
 	[path fill];
-    else
-	[path stroke];
+    }
+
+    assert(outlinecolour >= 0 && outlinecolour < fe->ncolours);
+    [fe->colours[outlinecolour] set];
+    [path stroke];
 }
 void draw_circle(frontend *fe, int cx, int cy, int radius,
-                 int fill, int colour)
+                 int fillcolour, int outlinecolour)
 {
     NSBezierPath *path = [NSBezierPath bezierPath];
 
     [[NSGraphicsContext currentContext] setShouldAntialias:YES];
 
-    assert(colour >= 0 && colour < fe->ncolours);
-    [fe->colours[colour] set];
-
     [path appendBezierPathWithArcWithCenter:NSMakePoint(cx + 0.5, cy + 0.5)
         radius:radius startAngle:0.0 endAngle:360.0];
 
     [path closePath];
 
-    if (fill)
+    if (fillcolour >= 0) {
+	assert(fillcolour >= 0 && fillcolour < fe->ncolours);
+	[fe->colours[fillcolour] set];
 	[path fill];
-    else
-	[path stroke];
+    }
+
+    assert(outlinecolour >= 0 && outlinecolour < fe->ncolours);
+    [fe->colours[outlinecolour] set];
+    [path stroke];
 }
 void draw_line(frontend *fe, int x1, int y1, int x2, int y2, int colour)
 {
diff --git a/pattern.c b/pattern.c
index b7c5334..7713ffd 100644
--- a/pattern.c
+++ b/pattern.c
@@ -1215,8 +1215,6 @@ void draw_text(frontend *fe, int x, int y, int fonttype, int fontsize,
                int align, int colour, char *text) {}
 void draw_rect(frontend *fe, int x, int y, int w, int h, int colour) {}
 void draw_line(frontend *fe, int x1, int y1, int x2, int y2, int colour) {}
-void draw_polygon(frontend *fe, int *coords, int npoints,
-                  int fill, int colour) {}
 void clip(frontend *fe, int x, int y, int w, int h) {}
 void unclip(frontend *fe) {}
 void start_draw(frontend *fe) {}
diff --git a/puzzles.h b/puzzles.h
index 2bb90c1..57445ab 100644
--- a/puzzles.h
+++ b/puzzles.h
@@ -136,9 +136,9 @@ void draw_text(frontend *fe, int x, int y, int fonttype, int fontsize,
 void draw_rect(frontend *fe, int x, int y, int w, int h, int colour);
 void draw_line(frontend *fe, int x1, int y1, int x2, int y2, int colour);
 void draw_polygon(frontend *fe, int *coords, int npoints,
-                  int fill, int colour);
+                  int fillcolour, int outlinecolour);
 void draw_circle(frontend *fe, int cx, int cy, int radius,
-                 int fill, int colour);
+                 int fillcolour, int outlinecolour);
 void clip(frontend *fe, int x, int y, int w, int h);
 void unclip(frontend *fe);
 void start_draw(frontend *fe);
diff --git a/samegame.c b/samegame.c
index ed516e2..a384c0b 100644
--- a/samegame.c
+++ b/samegame.c
@@ -883,13 +883,11 @@ static void game_redraw(frontend *fe, game_drawstate *ds, game_state *oldstate,
 	coords[9] = COORD(state->params.h) + HIGHLIGHT_WIDTH - 1 - TILE_GAP;
 	coords[6] = coords[8] + TILE_SIZE;
 	coords[7] = coords[9] - TILE_SIZE;
-	draw_polygon(fe, coords, 5, TRUE, COL_HIGHLIGHT);
-	draw_polygon(fe, coords, 5, FALSE, COL_HIGHLIGHT);
+	draw_polygon(fe, coords, 5, COL_HIGHLIGHT, COL_HIGHLIGHT);
 
 	coords[1] = COORD(0) - HIGHLIGHT_WIDTH;
 	coords[0] = COORD(0) - HIGHLIGHT_WIDTH;
-	draw_polygon(fe, coords, 5, TRUE, COL_LOWLIGHT);
-	draw_polygon(fe, coords, 5, FALSE, COL_LOWLIGHT);
+	draw_polygon(fe, coords, 5, COL_LOWLIGHT, COL_LOWLIGHT);
 
 	ds->started = 1;
     }
diff --git a/sixteen.c b/sixteen.c
index 1b6107c..72585c1 100644
--- a/sixteen.c
+++ b/sixteen.c
@@ -778,13 +778,11 @@ static void draw_tile(frontend *fe, game_drawstate *ds,
         coords[3] = y;
         coords[4] = x;
         coords[5] = y + TILE_SIZE - 1;
-        draw_polygon(fe, coords, 3, TRUE, COL_LOWLIGHT);
-        draw_polygon(fe, coords, 3, FALSE, COL_LOWLIGHT);
+        draw_polygon(fe, coords, 3, COL_LOWLIGHT, COL_LOWLIGHT);
 
         coords[0] = x;
         coords[1] = y;
-        draw_polygon(fe, coords, 3, TRUE, COL_HIGHLIGHT);
-        draw_polygon(fe, coords, 3, FALSE, COL_HIGHLIGHT);
+        draw_polygon(fe, coords, 3, COL_HIGHLIGHT, COL_HIGHLIGHT);
 
         draw_rect(fe, x + HIGHLIGHT_WIDTH, y + HIGHLIGHT_WIDTH,
                   TILE_SIZE - 2*HIGHLIGHT_WIDTH, TILE_SIZE - 2*HIGHLIGHT_WIDTH,
@@ -816,8 +814,7 @@ static void draw_arrow(frontend *fe, game_drawstate *ds,
     POINT(5, 3 * TILE_SIZE / 8, TILE_SIZE / 2);   /* left concave */
     POINT(6,     TILE_SIZE / 4, TILE_SIZE / 2);   /* left corner */
 
-    draw_polygon(fe, coords, 7, TRUE, COL_LOWLIGHT);
-    draw_polygon(fe, coords, 7, FALSE, COL_TEXT);
+    draw_polygon(fe, coords, 7, COL_LOWLIGHT, COL_TEXT);
 }
 
 static void game_redraw(frontend *fe, game_drawstate *ds, game_state *oldstate,
@@ -855,13 +852,11 @@ static void game_redraw(frontend *fe, game_drawstate *ds, game_state *oldstate,
         coords[9] = COORD(state->h) + HIGHLIGHT_WIDTH - 1;
         coords[6] = coords[8] + TILE_SIZE;
         coords[7] = coords[9] - TILE_SIZE;
-        draw_polygon(fe, coords, 5, TRUE, COL_HIGHLIGHT);
-        draw_polygon(fe, coords, 5, FALSE, COL_HIGHLIGHT);
+        draw_polygon(fe, coords, 5, COL_HIGHLIGHT, COL_HIGHLIGHT);
 
         coords[1] = COORD(0) - HIGHLIGHT_WIDTH;
         coords[0] = COORD(0) - HIGHLIGHT_WIDTH;
-        draw_polygon(fe, coords, 5, TRUE, COL_LOWLIGHT);
-        draw_polygon(fe, coords, 5, FALSE, COL_LOWLIGHT);
+        draw_polygon(fe, coords, 5, COL_LOWLIGHT, COL_LOWLIGHT);
 
         /*
          * Arrows for making moves.
diff --git a/solo.c b/solo.c
index b9510e2..cfbb869 100644
--- a/solo.c
+++ b/solo.c
@@ -2215,7 +2215,7 @@ static void draw_number(frontend *fe, game_drawstate *ds, game_state *state,
         coords[3] = cy;
         coords[4] = cx;
         coords[5] = cy+ch/2;
-        draw_polygon(fe, coords, 3, TRUE, COL_HIGHLIGHT);
+        draw_polygon(fe, coords, 3, COL_HIGHLIGHT, COL_HIGHLIGHT);
     }
 
     /* new number needs drawing? */
@@ -2438,7 +2438,7 @@ void draw_text(frontend *fe, int x, int y, int fonttype, int fontsize,
 void draw_rect(frontend *fe, int x, int y, int w, int h, int colour) {}
 void draw_line(frontend *fe, int x1, int y1, int x2, int y2, int colour) {}
 void draw_polygon(frontend *fe, int *coords, int npoints,
-                  int fill, int colour) {}
+                  int fillcolour, int outlinecolour) {}
 void clip(frontend *fe, int x, int y, int w, int h) {}
 void unclip(frontend *fe) {}
 void start_draw(frontend *fe) {}
diff --git a/twiddle.c b/twiddle.c
index fc12411..92f5db3 100644
--- a/twiddle.c
+++ b/twiddle.c
@@ -880,29 +880,29 @@ static void draw_tile(frontend *fe, game_drawstate *ds, game_state *state,
     coords[2] = x + TILE_SIZE - 1;
     coords[3] = y;
     rotate(coords+2, rot);
-    draw_polygon(fe, coords, 3, TRUE, rot ? rot->rc : COL_LOWLIGHT);
-    draw_polygon(fe, coords, 3, FALSE, rot ? rot->rc : COL_LOWLIGHT);
+    draw_polygon(fe, coords, 3, rot ? rot->rc : COL_LOWLIGHT,
+		 rot ? rot->rc : COL_LOWLIGHT);
 
     /* Bottom side. */
     coords[2] = x;
     coords[3] = y + TILE_SIZE - 1;
     rotate(coords+2, rot);
-    draw_polygon(fe, coords, 3, TRUE, rot ? rot->bc : COL_LOWLIGHT);
-    draw_polygon(fe, coords, 3, FALSE, rot ? rot->bc : COL_LOWLIGHT);
+    draw_polygon(fe, coords, 3, rot ? rot->bc : COL_LOWLIGHT,
+		 rot ? rot->bc : COL_LOWLIGHT);
 
     /* Left side. */
     coords[0] = x;
     coords[1] = y;
     rotate(coords+0, rot);
-    draw_polygon(fe, coords, 3, TRUE, rot ? rot->lc : COL_HIGHLIGHT);
-    draw_polygon(fe, coords, 3, FALSE, rot ? rot->lc : COL_HIGHLIGHT);
+    draw_polygon(fe, coords, 3, rot ? rot->lc : COL_HIGHLIGHT,
+		 rot ? rot->lc : COL_HIGHLIGHT);
 
     /* Top side. */
     coords[2] = x + TILE_SIZE - 1;
     coords[3] = y;
     rotate(coords+2, rot);
-    draw_polygon(fe, coords, 3, TRUE, rot ? rot->tc : COL_HIGHLIGHT);
-    draw_polygon(fe, coords, 3, FALSE, rot ? rot->tc : COL_HIGHLIGHT);
+    draw_polygon(fe, coords, 3, rot ? rot->tc : COL_HIGHLIGHT,
+		 rot ? rot->tc : COL_HIGHLIGHT);
 
     /*
      * Now the main blank area in the centre of the tile.
@@ -920,8 +920,7 @@ static void draw_tile(frontend *fe, game_drawstate *ds, game_state *state,
 	coords[6] = x + TILE_SIZE - 1 - HIGHLIGHT_WIDTH;
 	coords[7] = y + HIGHLIGHT_WIDTH;
 	rotate(coords+6, rot);
-	draw_polygon(fe, coords, 4, TRUE, flash_colour);
-	draw_polygon(fe, coords, 4, FALSE, flash_colour);
+	draw_polygon(fe, coords, 4, flash_colour, flash_colour);
     } else {
 	draw_rect(fe, x + HIGHLIGHT_WIDTH, y + HIGHLIGHT_WIDTH,
 		  TILE_SIZE - 2*HIGHLIGHT_WIDTH, TILE_SIZE - 2*HIGHLIGHT_WIDTH,
@@ -967,8 +966,7 @@ static void draw_tile(frontend *fe, game_drawstate *ds, game_state *state,
 	coords[4] = cx - displ * ydx;
 	coords[5] = cy - displ * ydy;
 	rotate(coords+4, rot);
-	draw_polygon(fe, coords, 3, TRUE, COL_LOWLIGHT_GENTLE);
-	draw_polygon(fe, coords, 3, FALSE, COL_LOWLIGHT_GENTLE);
+	draw_polygon(fe, coords, 3, COL_LOWLIGHT_GENTLE, COL_LOWLIGHT_GENTLE);
     }
 
     coords[0] = x + TILE_SIZE/2;
@@ -1082,13 +1080,11 @@ static void game_redraw(frontend *fe, game_drawstate *ds, game_state *oldstate,
         coords[9] = COORD(state->h) + HIGHLIGHT_WIDTH - 1;
         coords[6] = coords[8] + TILE_SIZE;
         coords[7] = coords[9] - TILE_SIZE;
-        draw_polygon(fe, coords, 5, TRUE, COL_HIGHLIGHT);
-        draw_polygon(fe, coords, 5, FALSE, COL_HIGHLIGHT);
+        draw_polygon(fe, coords, 5, COL_HIGHLIGHT, COL_HIGHLIGHT);
 
         coords[1] = COORD(0) - HIGHLIGHT_WIDTH;
         coords[0] = COORD(0) - HIGHLIGHT_WIDTH;
-        draw_polygon(fe, coords, 5, TRUE, COL_LOWLIGHT);
-        draw_polygon(fe, coords, 5, FALSE, COL_LOWLIGHT);
+        draw_polygon(fe, coords, 5, COL_LOWLIGHT, COL_LOWLIGHT);
 
         ds->started = TRUE;
     }
diff --git a/windows.c b/windows.c
index df3de01..57673e1 100644
--- a/windows.c
+++ b/windows.c
@@ -333,26 +333,28 @@ void draw_line(frontend *fe, int x1, int y1, int x2, int y2, int colour)
 }
 
 void draw_circle(frontend *fe, int cx, int cy, int radius,
-                 int fill, int colour)
+                 int fillcolour, int outlinecolour)
 {
-    if (fill) {
-	HBRUSH oldbrush = SelectObject(fe->hdc_bm, fe->brushes[colour]);
-	HPEN oldpen = SelectObject(fe->hdc_bm, fe->pens[colour]);
+    assert(outlinecolour >= 0);
+
+    if (fillcolour >= 0) {
+	HBRUSH oldbrush = SelectObject(fe->hdc_bm, fe->brushes[fillcolour]);
+	HPEN oldpen = SelectObject(fe->hdc_bm, fe->pens[outlinecolour]);
 	Ellipse(fe->hdc_bm, cx - radius, cy - radius,
 		cx + radius + 1, cy + radius + 1);
 	SelectObject(fe->hdc_bm, oldbrush);
 	SelectObject(fe->hdc_bm, oldpen);
     } else {
-	HPEN oldpen = SelectObject(fe->hdc_bm, fe->pens[colour]);
-        Arc(fe->hdc_bm, cx - radius, cy - radius,
-            cx + radius + 1, cy + radius + 1,
-            cx - radius, cy, cx - radius, cy);
+	HPEN oldpen = SelectObject(fe->hdc_bm, fe->pens[outlinecolour]);
+	Arc(fe->hdc_bm, cx - radius, cy - radius,
+	    cx + radius + 1, cy + radius + 1,
+	    cx - radius, cy, cx - radius, cy);
 	SelectObject(fe->hdc_bm, oldpen);
     }
 }
 
 void draw_polygon(frontend *fe, int *coords, int npoints,
-                  int fill, int colour)
+                  int fillcolour, int outlinecolour)
 {
     POINT *pts = snewn(npoints+1, POINT);
     int i;
@@ -363,14 +365,16 @@ void draw_polygon(frontend *fe, int *coords, int npoints,
 	pts[i].y = coords[j*2+1];
     }
 
-    if (fill) {
-	HBRUSH oldbrush = SelectObject(fe->hdc_bm, fe->brushes[colour]);
-	HPEN oldpen = SelectObject(fe->hdc_bm, fe->pens[colour]);
+    assert(outlinecolour >= 0);
+
+    if (fillcolour >= 0) {
+	HBRUSH oldbrush = SelectObject(fe->hdc_bm, fe->brushes[fillcolour]);
+	HPEN oldpen = SelectObject(fe->hdc_bm, fe->pens[outlinecolour]);
 	Polygon(fe->hdc_bm, pts, npoints);
 	SelectObject(fe->hdc_bm, oldbrush);
 	SelectObject(fe->hdc_bm, oldpen);
     } else {
-	HPEN oldpen = SelectObject(fe->hdc_bm, fe->pens[colour]);
+	HPEN oldpen = SelectObject(fe->hdc_bm, fe->pens[outlinecolour]);
 	Polyline(fe->hdc_bm, pts, npoints+1);
 	SelectObject(fe->hdc_bm, oldpen);
     }