diff --git a/src/ctxt.h b/src/ctxt.h
index 747477e..f9b591a 100644
--- a/src/ctxt.h
+++ b/src/ctxt.h
@@ -11,6 +11,7 @@ struct ax_window;
 struct ax_window_builder;
 struct ax_backend;
 struct ax_evt_list;
+struct ax_graphics;
 
 struct ax_ctxt {
     struct rgn* init_rgn;
diff --git a/src/ctxt/window.c b/src/ctxt/window.c
index 1c9aa6a..a41d22d 100644
--- a/src/ctxt/window.c
+++ b/src/ctxt/window.c
@@ -1,6 +1,7 @@
+#include "window.h"
 #include "../concurrent/msg.h"
 #include "../concurrent/msgq.h"
-#include "window.h"
+#include "../geom/graphics.h"
 
 static inline const char* default_title(struct rgn* rgn)
 {
@@ -24,6 +25,8 @@ struct ax_window_builder* ax__window_builder_new(struct rgn* rgn)
     return winb;
 }
 
+static void draw_demo(struct ax_graphics* gr);
+
 struct ax_window* ax__window_builder_finish(
     struct ax_window_builder* winb,
     struct rgn* dst_rgn,
@@ -33,6 +36,8 @@ struct ax_window* ax__window_builder_finish(
         ralloc_typed(dst_rgn, struct ax_window, 1);
     pthread_mutex_init(&win->mx, NULL);
     rgn_pin(dst_rgn, &win->mx, (void*) pthread_mutex_destroy);
+    win->graphics = ax__graphics_new(dst_rgn);
+    draw_demo(win->graphics);
 
     struct ax_msg_make_window* m =
         msgq_begin_send_typed(req_window_mq, ax_msg_make_window);
@@ -45,3 +50,26 @@ struct ax_window* ax__window_builder_finish(
 
     return win;
 }
+
+static void draw_demo(struct ax_graphics* gr)
+{
+    struct ax_glyph* g;
+
+    ax__graphics_clear(gr, 0xffffff);
+
+    g = ax__graphics_push(gr);
+    g->ty = AX_GLYPH_RECT;
+    g->d.rect.x = 5;
+    g->d.rect.y = 5;
+    g->d.rect.w = 300;
+    g->d.rect.h = 200;
+    g->d.rect.f = 0xcc0044;
+
+    g = ax__graphics_push(gr);
+    g->ty = AX_GLYPH_RECT;
+    g->d.rect.x = 75;
+    g->d.rect.y = 23;
+    g->d.rect.w = 150;
+    g->d.rect.h = 400;
+    g->d.rect.f = 0x4444ff;
+}
diff --git a/src/ctxt/window.h b/src/ctxt/window.h
index e116405..b09eb8c 100644
--- a/src/ctxt/window.h
+++ b/src/ctxt/window.h
@@ -7,7 +7,7 @@
 
 struct msgq;
 struct ax_backend;
-struct ax_window_h;
+struct ax_graphics;
 
 #define WINDOW_BUILDER_DESIRED_REGION_SIZE SMALL
 
@@ -17,6 +17,7 @@ enum ax_window_flags {
 
 struct ax_window {
     pthread_mutex_t mx;
+    struct ax_graphics* graphics;
 };
 
 struct ax_window_builder {
diff --git a/src/util.h b/src/util.h
index 412fc63..35238e2 100644
--- a/src/util.h
+++ b/src/util.h
@@ -19,7 +19,7 @@
     ASSERT(0, "not implemented")
 
 #define IMPOSSIBLE_(what) \
-    ASSERT(0, "unreachable: " what)
+    ASSERT(0, "unreachable: %s", what)
 
 // hard to explain why this is necessary ...
 #define IMPOSSIBLE(x) IMPOSSIBLE_(x)