diff --git a/ex11.mu b/ex11.mu
new file mode 100644
index 00000000..bbe16d5a
--- /dev/null
+++ b/ex11.mu
@@ -0,0 +1,71 @@
+# Demo of an interactive app: controlling a Bezier curve on screen
+
+fn main screen: (addr screen), keyboard: (addr keyboard), data-disk: (addr disk) {
+  var p0-storage: point
+  var p0/ecx: (addr point) <- address p0-storage
+  initialize-point p0, 1 1
+  var p1-storage: point
+  var p1/edx: (addr point) <- address p1-storage
+  initialize-point p1, 0x80 0x100
+  var p2-storage: point
+  var p2/ebx: (addr point) <- address p2-storage
+  initialize-point p2, 0x200 0x140
+  render screen, p0, p1, p2
+}
+
+type point {
+  x: int
+  y: int
+}
+
+fn initialize-point _p: (addr point), x: int, y: int {
+  var p/esi: (addr point) <- copy _p
+  var dest/eax: (addr int) <- get p, x
+  var src/ecx: int <- copy x
+  copy-to *dest, src
+  dest <- get p, y
+  src <- copy y
+  copy-to *dest, src
+}
+
+fn render screen: (addr screen), p0: (addr point), p1: (addr point), p2: (addr point) {
+  # control lines
+  line    screen, p0, p1,                 7/color
+  line    screen, p1, p2,                 7/color
+  # curve above control lines
+  bezier  screen, p0, p1, p2,             0xc/color
+  # points above curve
+  disc    screen, p0,           3/radius, 7/color   0xf/border
+  disc    screen, p1,           3/radius, 7/color   0xf/border
+  disc    screen, p2,           3/radius, 7/color   0xf/border
+}
+
+fn bezier screen: (addr screen), _p0: (addr point), _p1: (addr point), _p2: (addr point), color: int {
+  var p0/esi: (addr point) <- copy _p0
+  var x0/ecx: (addr int) <- get p0, x
+  var y0/edx: (addr int) <- get p0, y
+  var p1/esi: (addr point) <- copy _p1
+  var x1/ebx: (addr int) <- get p1, x
+  var y1/eax: (addr int) <- get p1, y
+  var p2/esi: (addr point) <- copy _p2
+  var x2/edi: (addr int) <- get p2, x
+  var y2/esi: (addr int) <- get p2, y
+  draw-monotonic-bezier screen, *x0 *y0, *x1 *y1, *x2 *y2, color
+}
+
+fn line screen: (addr screen), _p0: (addr point), _p1: (addr point), color: int {
+  var p0/esi: (addr point) <- copy _p0
+  var x0/ecx: (addr int) <- get p0, x
+  var y0/edx: (addr int) <- get p0, y
+  var p1/esi: (addr point) <- copy _p1
+  var x1/ebx: (addr int) <- get p1, x
+  var y1/eax: (addr int) <- get p1, y
+  draw-line screen, *x0 *y0, *x1 *y1, color
+}
+
+fn disc screen: (addr screen), _p: (addr point), radius: int, color: int, border-color: int {
+  var p/esi: (addr point) <- copy _p
+  var x/ecx: (addr int) <- get p, x
+  var y/edx: (addr int) <- get p, y
+  draw-disc screen, *x *y, radius, color, border-color
+}
diff --git a/hest-life.mu b/hest-life.mu
deleted file mode 100644
index 552c42ae..00000000
--- a/hest-life.mu
+++ /dev/null
@@ -1,8 +0,0 @@
-fn main screen: (addr screen), keyboard: (addr keyboard), data-disk: (addr disk) {
-  draw-line             screen,         1 1,   0x80 0x100,               7/color
-  draw-line             screen,  0x80 0x100,  0x200 0x140,               7/color
-  draw-monotonic-bezier screen,         1 1,   0x80 0x100,  0x200 0x140, 0xc/color
-  draw-disc             screen,         1 1,            3,               7/color 0xf/border
-  draw-disc             screen,  0x80 0x100,            3,               7/color 0xf/border
-  draw-disc             screen, 0x200 0x140,            3,               7/color 0xf/border
-}