diff --git a/nested-client.c b/nested-client.c
--- a/nested-client.c
+++ b/nested-client.c
@@ -205,9 +205,24 @@
 int main(int argc,char **argv) {
     signal(SIGTERM,stop);
     const char *placement=argc>1?argv[1]:"b_cross";
+    /* CONTRACT: vertical positioner anchors remain inside the toplevel's
+     * effective window geometry, which defaults to its buffer bounds. */
+    if (!strncmp(placement,"v_",2)) top.height=575;
     if (!strcmp(placement,"visible")) {
         a.anchor_x=50; a.anchor_y=80; a.width=250;
         b.anchor_x=20; b.anchor_y=60; b.width=170;
+    } else if (!strcmp(placement,"v_visible")) {
+        a.anchor_x=50; a.anchor_y=80; a.width=250;
+        b.anchor_x=20; b.anchor_y=60; b.width=170;
+    } else if (!strcmp(placement,"v_b_cross")) {
+        /* WHY: only B's requested rectangle reaches below y=600 when the
+         * tiled toplevel content begins near y=25. Configure and pixels
+         * remain the authority for the actual crossing. */
+        a.anchor_x=50; a.anchor_y=350; a.width=250;
+        b.anchor_x=20; b.anchor_y=155; b.width=170;
+    } else if (!strcmp(placement,"v_both_cross")) {
+        a.anchor_x=50; a.anchor_y=480; a.width=250;
+        b.anchor_x=20; b.anchor_y=80; b.width=170;
     } else if (!strcmp(placement,"both_cross")) {
         a.anchor_x=350; a.anchor_y=80; a.width=350;
         b.anchor_x=160; b.anchor_y=60; b.width=300;