Drawing artifact with round check buttons in menu under Cairo (#792)

src/fl_gtk.cxx

@@ -232,7 +232,9 @@ static void gtk_round_up_box(int x, int y, int w, int h, Fl_Color c) {
 
 static void gtk_round_down_box(int x, int y, int w, int h, Fl_Color c) {
   gtk_color(c);
+  fl_antialias(0);  // fix for issue #792
   draw(FILL,        x,   y, w,   h, 2);
+  fl_antialias(1);  // fix for issue #792
 
   gtk_color(fl_color_average(FL_WHITE, c, 0.1f));
   draw(LOWER_RIGHT, x+1, y, w-2, h, 2);

src/fl_oxy.cxx

@@ -217,9 +217,13 @@ static void _oxy_rounded_box_(int x, int y, int w, int h, Fl_Color bg) {
     fl_pie(x + w - h, y, h, h, 0.0, 90.0);    // top-left quarter of circle
     fl_pie(x + w - h, y, h, h, 270.0, 360.0); // bottom-left quarter of circle
   } else {
+    fl_antialias(0);  // fix for issue #792
     fl_pie(x, y, w, w, 0.0, 180.0);           // top half of circle
+    fl_antialias(1);  // fix for issue #792
     fl_rectf(x, y + w / 2, w, h - w);         // rectangle between top and bottom half-circle
+    fl_antialias(0);  // fix for issue #792
     fl_pie(x, y + h - w, w, w, 180.0, 360.0); // bottom half of circle
+    fl_antialias(1);  // fix for issue #792
   }
 }
 

src/fl_round_box.cxx

@@ -73,7 +73,9 @@ extern const uchar* fl_gray_ramp();
 
 void fl_round_down_box(int x, int y, int w, int h, Fl_Color bgcolor) {
   const uchar *g = fl_gray_ramp();
+  fl_antialias(0);  // fix for issue #792
   draw(FILL,        x,   y, w,   h, 2, Fl::box_color(bgcolor));
+  fl_antialias(1);  // fix for issue #792
   draw(UPPER_LEFT,  x+1, y, w-2, h, 0, (Fl_Color)g[(int)'N']);
   draw(UPPER_LEFT,  x+1, y, w-2, h, 1, (Fl_Color)g[(int)'H']);
   draw(UPPER_LEFT,  x,   y, w,   h, 0, (Fl_Color)g[(int)'N']);