diff --git a/README.md b/README.md
index 6f0b1edfc..219bee58b 100644
--- a/README.md
+++ b/README.md
@@ -420,6 +420,8 @@ up someday **FIXME**.
     make the Internet great. It probably violates any number of copyrights. C'est la vie.
 * Mark Ferrari, master of the pixel, for no good reason allowed me to reproduce
     his incredible and groundbreaking color-cycling artwork. Thanks Mark!
+* The world map image was made by [Vecteezy](https://www.vecteezy.com/free-vector/world-map),
+    and is used according to the terms of their License.
 * Finally, the [demoscene](https://en.wikipedia.org/wiki/Demoscene) and general
     l33t scene of the 90s and early twenty-first century endlessly inspired a
     young hax0r. There is great joy in computing; no one will drive us from
diff --git a/USAGE.md b/USAGE.md
index 237446829..119feec2b 100644
--- a/USAGE.md
+++ b/USAGE.md
@@ -1130,11 +1130,11 @@ ncplane_double_box_sized(struct ncplane* n, uint32_t attr, uint64_t channels,
 Similarly, areas can be filled with a cell.
 
 ```c
-// Starting at the specified coordinate, if it has no glyph, 'c' is copied into
-// it. We do the same to all cardinally-connected glyphless cells, filling in
-// everything behind a boundary. Returns the number of cells polyfilled. An
-// invalid initial y, x is an error. Returns the number of cells filled, or
-// -1 on error.
+// Starting at the specified coordinate, if its glyph is different from that of
+// 'c', 'c' is copied into it, and the original glyph is considered the fill
+// target. We do the same to all cardinally-connected cells having this same
+// fill target. Returns the number of cells polyfilled. An invalid initial y, x
+// is an error. Returns the number of cells filled, or -1 on error.
 int ncplane_polyfill_yx(struct ncplane* n, int y, int x, const cell* c);
 
 // Draw a gradient with its upper-left corner at the current cursor position,
diff --git a/data/worldmap.png b/data/worldmap.png
new file mode 100644
index 000000000..6ab04615a
Binary files /dev/null and b/data/worldmap.png differ
diff --git a/doc/man/man1/notcurses-demo.1.md b/doc/man/man1/notcurses-demo.1.md
index a71b10c74..3480abc05 100644
--- a/doc/man/man1/notcurses-demo.1.md
+++ b/doc/man/man1/notcurses-demo.1.md
@@ -22,17 +22,18 @@ a way that is going to prevent notcurses from working.
 
 The demonstrations include (see NOTES below):
 
-* (i)ntro—a setting of tone
+* (a)ll—scroll all the glyphs of your font
 * (b)oxes—pulsating boxes with a transparent center
 * (c)hunli—the strongest woman in the world
 * (e)agle—they took some time off my life, back in the day
-* (a)ll—scroll all the glyphs of your font
 * (f)allin'—the screen falls apart under heavy blows
 * (g)rid—a gradient of color lain atop a great grid
 * (h)ighcon—high contrast text atop various colors
+* (i)ntro—a setting of tone
 * (j)ungle—low-bandwidth color cycling reveals ancient ruins
 * (l)uigi—a dashing Apennine plumber in a world of fire
 * (n)ormal—a normal map of a friend, with effects
+* (o)utro—a message of hope from the library's author
 * (q)rcode—quick response codes (from ISO/IEC 18004:2015)
 * (r)eel—demonstration of the ncreel high-level widget
 * (s)liders—a missing-piece puzzle made up of colorful blocks
@@ -41,7 +42,7 @@ The demonstrations include (see NOTES below):
 * (v)iew—images and a video are rendered as text
 * (w)hiteout—a great Nothing slowly robs the world of color
 * (x)ray—stimulate a logo with energy
-* (o)utro—a message of hope from the library's author
+* (y)ield—the best laid schemes o' mice an'men gang aft agley
 
 At any time, press 'q' to quit. The demo is best run in at least an 80x45 terminal.
 
@@ -70,7 +71,7 @@ At any time, press 'q' to quit. The demo is best run in at least an 80x45 termin
 **-V**: Print the program name and version, and exit with success.
 
 demospec: Select which demos to run, and what order to run them in. The
-default is **ixeathnbcgrwuvlsfjqo**. See above for a list of demos.
+default is **ixeaythnbcgrwuvlsfjqo**. See above for a list of demos.
 
 Default margins are all 0, and thus the full screen will be rendered. Using
 **-m**, margins can be supplied. Provide a single number to set all four margins
@@ -91,7 +92,7 @@ non-free under the Debian Free Software Guidelines. As a result, the
 are unavailable through the Debian package.
 
 If notcurses is built without multimedia support, the **chunli**, **eagle**,
-**outro**, **view**, and **xray** demos will be partially or wholly
+**outro**, **view**, **xray**, and **yield** demos will be partially or wholly
 unavailable. If notcurses is built without libqrcodegen, the **qrcode** demo
 will be unavailable.
 
diff --git a/include/notcurses/notcurses.h b/include/notcurses/notcurses.h
index 6a1aeb2fe..c02cf2207 100644
--- a/include/notcurses/notcurses.h
+++ b/include/notcurses/notcurses.h
@@ -1574,11 +1574,11 @@ ncplane_perimeter(struct ncplane* n, const cell* ul, const cell* ur,
   return ncplane_box_sized(n, ul, ur, ll, lr, hline, vline, dimy, dimx, ctlword);
 }
 
-// Starting at the specified coordinate, if it has no glyph, 'c' is copied into
-// it. We do the same to all cardinally-connected glyphless cells, filling in
-// everything behind a boundary. Returns the number of cells polyfilled. An
-// invalid initial y, x is an error. Returns the number of cells filled, or
-// -1 on error.
+// Starting at the specified coordinate, if its glyph is different from that of
+// 'c', 'c' is copied into it, and the original glyph is considered the fill
+// target. We do the same to all cardinally-connected cells having this same
+// fill target. Returns the number of cells polyfilled. An invalid initial y, x
+// is an error. Returns the number of cells filled, or -1 on error.
 API int ncplane_polyfill_yx(struct ncplane* n, int y, int x, const cell* c);
 
 // Draw a gradient with its upper-left corner at the current cursor position,
diff --git a/src/demo/demo.c b/src/demo/demo.c
index acc875c4f..4081849a9 100644
--- a/src/demo/demo.c
+++ b/src/demo/demo.c
@@ -19,7 +19,7 @@ static int democount;
 static demoresult* results;
 static char *datadir = NOTCURSES_SHARE;
 
-static const char DEFAULT_DEMO[] = "ixeathnbcgrwuvlsfjqo";
+static const char DEFAULT_DEMO[] = "ixeaythnbcgrwuvlsfjqo";
 
 atomic_bool interrupted = ATOMIC_VAR_INIT(false);
 // checked following demos, whether aborted, failed, or otherwise
@@ -96,8 +96,8 @@ static struct {
   { "uniblock", unicodeblocks_demo, false, },
   { "view", view_demo, true, },
   { "whiteout", witherworm_demo, false, },
-  {"xray", xray_demo, false, },
-  { NULL, NULL, false, },
+  { "xray", xray_demo, false, },
+  { "yield", yield_demo, false, },
   { NULL, NULL, false, },
 };
 
diff --git a/src/demo/demo.h b/src/demo/demo.h
index c55bd92ee..50637b8a6 100644
--- a/src/demo/demo.h
+++ b/src/demo/demo.h
@@ -43,6 +43,7 @@ int grid_demo(struct notcurses* nc);
 int fallin_demo(struct notcurses* nc);
 int highcontrast_demo(struct notcurses* nc);
 int jungle_demo(struct notcurses* nc);
+int yield_demo(struct notcurses* nc);
 int normal_demo(struct notcurses* nc);
 int sliding_puzzle_demo(struct notcurses* nc);
 int view_demo(struct notcurses* nc);
diff --git a/src/demo/yield.c b/src/demo/yield.c
new file mode 100644
index 000000000..8f605da32
--- /dev/null
+++ b/src/demo/yield.c
@@ -0,0 +1,39 @@
+#include "demo.h"
+
+int yield_demo(struct notcurses* nc){
+  if(!notcurses_canopen_images(nc)){
+    return 0;
+  }
+  int dimy, dimx;
+  struct ncplane* std = notcurses_stddim_yx(nc, &dimy, &dimx);
+  char* pic = find_data("worldmap.png");
+  nc_err_e err;
+  struct ncvisual* wmv = ncvisual_from_file(pic, &err);
+  free(pic);
+  if(wmv == NULL){
+    return -1;
+  }
+  struct ncvisual_options vopts = {
+    .n = std,
+    .scaling = NCSCALE_STRETCH,
+    .blitter = NCBLIT_2x2,
+  };
+  if(ncvisual_render(nc, wmv, &vopts) == NULL){
+    ncvisual_destroy(wmv);
+    return -1;
+  }
+  DEMO_RENDER(nc);
+  demo_nanosleep(nc, &demodelay);
+
+  cell c = CELL_SIMPLE_INITIALIZER('*');
+  cell_set_fg_rgb(&c, 0xff, 0, 0);
+  cell_set_bg_rgb(&c, 0xff, 0, 0);
+  for(int i = 0 ; i < 128 ; ++i){
+    // FIXME
+    // don't try to use polyfill; work directly on the ncvisual instead
+  }
+  cell_release(std, &c);
+
+  ncvisual_destroy(wmv);
+  return 0;
+}
diff --git a/src/lib/fill.c b/src/lib/fill.c
index 017d0e524..208a55feb 100644
--- a/src/lib/fill.c
+++ b/src/lib/fill.c
@@ -20,7 +20,7 @@ void ncplane_greyscale(ncplane *n){
 // success. so a return of 0 means there's no work to be done here, and N means
 // we did some work here, filling everything we could reach. out-of-plane is 0.
 static int
-ncplane_polyfill_recurse(ncplane* n, int y, int x, const cell* c){
+ncplane_polyfill_recurse(ncplane* n, int y, int x, const cell* c, const char* targ){
   if(y >= n->leny || x >= n->lenx){
     return 0; // not fillable
   }
@@ -28,26 +28,29 @@ ncplane_polyfill_recurse(ncplane* n, int y, int x, const cell* c){
     return 0; // not fillable
   }
   cell* cur = &n->fb[nfbcellidx(n, y, x)];
-  if(cur->gcluster){
-    return 0; // glyph, not polyfillable
+  char* glust = cell_strdup(n, cur);
+  if(strcmp(glust, targ)){
+    free(glust);
+    return 0;
   }
+  free(glust);
   if(cell_duplicate(n, cur, c) < 0){
     return -1;
   }
   int r, ret = 1;
-  if((r = ncplane_polyfill_recurse(n, y - 1, x, c)) < 0){
+  if((r = ncplane_polyfill_recurse(n, y - 1, x, c, targ)) < 0){
     return -1;
   }
   ret += r;
-  if((r = ncplane_polyfill_recurse(n, y + 1, x, c)) < 0){
+  if((r = ncplane_polyfill_recurse(n, y + 1, x, c, targ)) < 0){
     return -1;
   }
   ret += r;
-  if((r = ncplane_polyfill_recurse(n, y, x - 1, c)) < 0){
+  if((r = ncplane_polyfill_recurse(n, y, x - 1, c, targ)) < 0){
     return -1;
   }
   ret += r;
-  if((r = ncplane_polyfill_recurse(n, y, x + 1, c)) < 0){
+  if((r = ncplane_polyfill_recurse(n, y, x + 1, c, targ)) < 0){
     return -1;
   }
   ret += r;
@@ -57,11 +60,25 @@ ncplane_polyfill_recurse(ncplane* n, int y, int x, const cell* c){
 // at the initial step only, invalid y, x is an error, so explicitly check.
 int ncplane_polyfill_yx(ncplane* n, int y, int x, const cell* c){
   int ret = -1;
-  if(c->gcluster){ // can't polyfill with a null EGC
-    if(y < n->leny && x < n->lenx){
-      if(y >= 0 && x >= 0){
-        ret = ncplane_polyfill_recurse(n, y, x, c);
+  if(y < n->leny && x < n->lenx){
+    if(y >= 0 && x >= 0){
+      if(y >= n->leny || x >= n->lenx){
+        return -1; // not fillable
       }
+      if(y < 0 || x < 0){
+        return -1; // not fillable
+      }
+      cell* cur = &n->fb[nfbcellidx(n, y, x)];
+      char* targ = cell_strdup(n, cur);
+      char* fillegc = cell_strdup(n, c);
+      if(strcmp(fillegc, targ) == 0){
+        free(targ);
+        free(fillegc);
+        return 0;
+      }
+      free(fillegc);
+      ret = ncplane_polyfill_recurse(n, y, x, c, targ);
+      free(targ);
     }
   }
   return ret;
diff --git a/src/view/view.cpp b/src/view/view.cpp
index 4f132ed25..4c1e0b61d 100644
--- a/src/view/view.cpp
+++ b/src/view/view.cpp
@@ -99,7 +99,6 @@ auto perframe(struct ncvisual* ncv, struct ncvisual_options* vopts,
   clock_gettime(CLOCK_MONOTONIC, &interval);
   uint64_t nsnow = timespec_to_ns(&interval);
   uint64_t absnow = timespec_to_ns(abstime);
-  bool paused = false;
   if(absnow > nsnow){
     ns_to_timespec(absnow - nsnow, &interval);
     char32_t keyp;
diff --git a/tests/fills.cpp b/tests/fills.cpp
index 6964a54ed..0e846ac60 100644
--- a/tests/fills.cpp
+++ b/tests/fills.cpp
@@ -40,8 +40,8 @@ TEST_CASE("Fills") {
     REQUIRE(nullptr != pfn);
     CHECK(16 == ncplane_polyfill_yx(pfn, 0, 0, &c));
     CHECK(0 < ncplane_putc_yx(pfn, 0, 0, &c));
-    // Trying to fill the origin ought fill zero cells
-    CHECK(0 == ncplane_polyfill_yx(pfn, 0, 0, &c));
+    // Trying to fill the origin ought now be rejected
+    CHECK(0 > ncplane_polyfill_yx(pfn, 0, 0, &c));
     CHECK(0 == notcurses_render(nc_));
     CHECK(0 == ncplane_destroy(pfn));
   }