diff --git a/crates/ui/src/docking/iconic_tests.rs b/crates/ui/src/docking/iconic_tests.rs
index 58a85fa5..0a353f2c 100644
--- a/crates/ui/src/docking/iconic_tests.rs
+++ b/crates/ui/src/docking/iconic_tests.rs
@@ -273,6 +273,27 @@ fn group_dropped_on_an_iconic_column_joins_as_an_icon_group() {
     assert!(first_column(&d.layout).iconic);
 }
 
+/// A group dropped on the window edge beside an iconic column at that edge docks in a new column
+/// there: the preview is the edge line alone, without the column's outline.
+#[test]
+fn an_edge_drop_next_to_an_iconic_column_highlights_only_the_edge() {
+    let mut layout = docked(&[&[1], &[2]], true);
+    layout.floating.push(Floating::single(vec![5, 6], 0, [300.0, 200.0, 240.0, 200.0]));
+    let mut d = DockDriver::new(layout, Content);
+    let bar = hit(&d, Hit::DragBar(5)).center();
+    let target = pos2(2.0, 300.0);
+    d.hold(bar, target);
+    let column = Rect::from_min_max(pos2(0.0, 14.0), pos2(36.0, 600.0));
+    assert!(d.filled(Rect::from_x_y_ranges(0.0..=4.0, 0.0..=600.0)), "the edge line");
+    assert!(!d.outlined(column.shrink(1.0)), "the iconic column is not outlined");
+    d.release(target);
+    let Some(Node::Split { first, .. }) = &d.layout.root else { panic!("{:?}", d.layout.root) };
+    let Node::Dock { columns, .. } = first.as_ref() else { panic!("{first:?}") };
+    let panels: Vec<Vec<u32>> = columns.iter().map(|c| c.groups.iter().flat_map(|g| g.panels.clone()).collect()).collect();
+    assert_eq!(panels, vec![vec![5, 6], vec![1, 2]]);
+    assert!(!columns[0].iconic && columns[1].iconic);
+}
+
 /// Every kind of gesture source has a rect, and dragging from it does something.
 #[test]
 fn hit_rects_cover_every_gesture_source() {
diff --git a/crates/ui/src/docking/render/dock.rs b/crates/ui/src/docking/render/dock.rs
index 4eaab778..878d909e 100644
--- a/crates/ui/src/docking/render/dock.rs
+++ b/crates/ui/src/docking/render/dock.rs
@@ -789,11 +789,15 @@ impl<P: Clone + Eq + Hash + Debug + Send + Sync + 'static> Renderer<'_, P> {
     }
 
     /// The line of a drop that shows no result rect: on the window edge, into an iconic column,
-    /// or any dock drop with [`DockStyle::side_edge_zones`].
-    pub(super) fn paint_drop_line(&self, ctx: &Context, line: Rect) {
+    /// or any dock drop with [`DockStyle::side_edge_zones`]. A line inside an iconic column also
+    /// outlines the column, unless it is on the window edge (`outer`): a column at that edge holds
+    /// the line, but the drop docks beside the column, not into it.
+    pub(super) fn paint_drop_line(&self, ctx: &Context, line: Rect, outer: bool) {
         if usable(line) {
             let painter = self.preview_painter(ctx);
-            self.iconic.outline(&painter, line, self.style);
+            if !outer {
+                self.iconic.outline(&painter, line, self.style);
+            }
             painter.rect_filled(line, 1.0, self.style.accent);
         }
     }
diff --git a/crates/ui/src/docking/render/preview.rs b/crates/ui/src/docking/render/preview.rs
index 65c15fd3..5404984e 100644
--- a/crates/ui/src/docking/render/preview.rs
+++ b/crates/ui/src/docking/render/preview.rs
@@ -599,12 +599,12 @@ impl<P: Clone + Eq + Hash + Debug + Send + Sync + 'static> Renderer<'_, P> {
             if self.style.side_edge_zones {
                 drop_preview(painter, proposal.preview.shrink(1.0), self.style.accent, filled);
             } else if matches!(proposal.placement, Placement::Edge(_)) {
-                self.paint_drop_line(ctx, proposal.preview);
+                self.paint_drop_line(ctx, proposal.preview, true);
             } else if beside {
                 let to = Target::At { anchor: proposal.anchor.clone(), placement: proposal.placement.clone() };
                 match self.result_rect(action(to), members) {
                     Some(rect) => tab_outline(painter, rect.shrink(1.0), self.style.accent),
-                    None => self.paint_drop_line(ctx, proposal.preview),
+                    None => self.paint_drop_line(ctx, proposal.preview, false),
                 }
             } else {
                 tab_outline(painter, proposal.preview.shrink(1.0), self.style.accent);
@@ -621,7 +621,7 @@ impl<P: Clone + Eq + Hash + Debug + Send + Sync + 'static> Renderer<'_, P> {
         let rect = (!self.style.side_edge_zones && !drop.outer).then_some(action).and_then(|action| self.result_rect(action, members));
         match rect {
             Some(rect) => tab_outline(painter, rect.shrink(1.0), self.style.accent),
-            None => self.paint_drop_line(ctx, drop.line),
+            None => self.paint_drop_line(ctx, drop.line, drop.outer),
         }
     }