Fix #541: a click on a selected object makes it the key object

With the Selection tool, a click (no drag, no modifier) on one object of a
selection of several makes it the key object (select.key); a click on the
key again lets it go. The key object is drawn with a thicker outline,
Align aligns to it (the Align panel shows Align to Key Object while there
is a key, and choosing Selection or Artboard lets it go), and
object.align without `to` aligns to the key when there is one, so the
Control bar's and the Properties panel's Align buttons do too. With a
spacing, Distribute Spacing keeps the key object still and spaces the
others from it, and it reports too few objects instead of indexing an
empty list.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

ROADMAP.md

@@ -4,7 +4,7 @@ VectorCraft is a clean-room, open-source, pure-Rust reimplementation of the Adob
 
 This file tracks **how far we are and what's left**. Time estimates are wall-clock hours of continuous Claude Opus 5.5 agent work (including builds and the CI gate), given both for **one agent** and for **4–6 parallel agents** on disjoint crates. They are counted from the remaining work (see [Parity estimate](#parity-estimate)), calibrated against measured throughput, and updated as work lands.
 
-_Last updated: 2026-10-09 (after M4.14–M4.98, M8.1–M8.20, M14.4–M14.7, the MCP prompts, resource templates, completions and logging, the 2026-10-07 issue fixes, the Layers panel rework and the 2026-10-08 community contributions: Pen and shape-tool modifiers, path editing, Layers, Artboards, Swatches/Brushes and dialogs, Japanese composition and PDF text, Hebrew/Arabic type, interface languages (Spanish among them), the font menu, saved selections, MCP and EPS, the missing-font export warning (#319), open paths in the Shape Builder (#374), PDF/`.ai` import keeping strokes live and hidden and nested layers (#372), per-corner Live Corners (#381), SVG type opening at the size it draws at (#396), the Wayland clipboard with copied-file paste (#398), ruler guides that can be selected, moved and deleted (#414), two batches of Preferences options that were stored but unused (#394), skeleton reads with `document.find` for large documents over MCP (#416) and anchors dragged with Direct Selection snapping to points, segments and smart guides, clipped SVG layers opening as clipping layers (#420), PDF/`.ai` layers read on pages of tens of millions of operators (#419), Document Color Mode putting RGB greys on the black plate on request and converting pattern tiles (#421) and movable dialogs with Offset Path's Joins dropdown (#423) and numeric fields scrubbed by dragging their label (#400), stroke weight presets in the stroke unit (#426), the Appearance panel's Opacity popup (#430), type on a path brackets, flip and Type on a Path Options that keep the type in place (#429), Layers rows dragged with a ghost and dropped on the trash or New Layer (#435), tool flyouts opening on a right or corner press (#436), tool flyouts torn off into floating toolbars (#437), the Shape Builder's erase mode deleting edges too (#439), installed fonts registered outside the font folders and fonts installed while the app runs listed in the font menus (#443), alike circular corners on rectangles that aren't square (#442), tool cursors as OS cursors so the pointer no longer trails over the canvas (#444), artboards copied and pasted with their art (#446), guides dragged out of the rulers snapping to the art's side midpoints and the artboards, artboard guides (#451), the toolbar's double arrow and Window › Toolbars › Double Column switching between one and two columns in any window height (#455), the Smart Guides display options and Snapping Tolerance (#394), Font Size and Leading combo boxes with preset lists in the Character and Properties panels and the Control bar (#458), screenshots pasted from the clipboard on macOS, Windows and the web (#457), the Properties panel's Fill and Stroke matching the Control bar's, Illustrator's Window menu panel keys (Shift+F7 for Align…) and Alt-wheel zoom whatever the wheel preference (Discord feedback), the point/area type widget (Discord feedback), groups in legacy Illustrator .ai files (Discord feedback), a rotating desktop log file (#465), image controls in the Control bar and Properties panel: Image Trace with its presets, Mask, Crop Image, Embed/Unembed, and an Image Trace object's preset, Expand and Release (Discord feedback), the Pen working as the Anchor Point tool with Alt held over a selected path's handles and anchors, and anchor buttons that convert, connect and cut paths at the selected anchors (Discord feedback), Japanese hanging punctuation (burasagari, #463), Escape leaving Presentation Mode with no screen mode saved across restarts, documents dropped on the desktop app opening as tabs of their own and a note that an `.ai` file's art off its artboards isn't in the part read (#472), Add/Delete Anchor Point tool icons drawn from the Pen tool's (#479), EPS import running more of PostScript Level 3 (patterns, Type 3 fonts, mesh shadings, masked images, VM and resource probes), and a preview that stands in saying why (Discord feedback, #466, #469, #474), chords with modifiers recorded in Edit › Keyboard Shortcuts (#487), Type Object Selection by Path Only (#394), Anti-aliased Artwork (#394), Show Pixel Grid (#394), pen and touch taps pressed and lifted within one frame clicking where they tapped and the Linux/Wayland pen-tablet workaround (#491), bounding-box resizes landing on the other objects' anchors and centres with labels, and the Rotate, Scale, Shear and Reflect tools snapping their drags (#482), Shift-drag marquees that toggle the objects or anchors they reach and a Lasso whose Alt subtraction keeps the rest of the selection (#483), the mouse wheel stepping the focused numeric field, the dialogs' and preferences' drag values made such fields (#485), Show The Home Screen When No Documents Are Open (#394), Numbers Without Units Are Points (#394), Auto-Collapse Iconic Panels (#394), the Contextual Task Bar moved by its handle and its More Options menu pinning and resetting its position, a designed macOS DMG window (#493), panels, panel groups and the Tools panel undocking into flLine truncated
+_Last updated: 2026-10-09 (after M4.14–M4.98, M8.1–M8.20, M14.4–M14.7, the MCP prompts, resource templates, completions and logging, the 2026-10-07 issue fixes, the Layers panel rework and the 2026-10-08 community contributions: Pen and shape-tool modifiers, path editing, Layers, Artboards, Swatches/Brushes and dialogs, Japanese composition and PDF text, Hebrew/Arabic type, interface languages (Spanish among them), the font menu, saved selections, MCP and EPS, the missing-font export warning (#319), open paths in the Shape Builder (#374), PDF/`.ai` import keeping strokes live and hidden and nested layers (#372), per-corner Live Corners (#381), SVG type opening at the size it draws at (#396), the Wayland clipboard with copied-file paste (#398), ruler guides that can be selected, moved and deleted (#414), two batches of Preferences options that were stored but unused (#394), skeleton reads with `document.find` for large documents over MCP (#416) and anchors dragged with Direct Selection snapping to points, segments and smart guides, clipped SVG layers opening as clipping layers (#420), PDF/`.ai` layers read on pages of tens of millions of operators (#419), Document Color Mode putting RGB greys on the black plate on request and converting pattern tiles (#421) and movable dialogs with Offset Path's Joins dropdown (#423) and numeric fields scrubbed by dragging their label (#400), stroke weight presets in the stroke unit (#426), the Appearance panel's Opacity popup (#430), type on a path brackets, flip and Type on a Path Options that keep the type in place (#429), Layers rows dragged with a ghost and dropped on the trash or New Layer (#435), tool flyouts opening on a right or corner press (#436), tool flyouts torn off into floating toolbars (#437), the Shape Builder's erase mode deleting edges too (#439), installed fonts registered outside the font folders and fonts installed while the app runs listed in the font menus (#443), alike circular corners on rectangles that aren't square (#442), tool cursors as OS cursors so the pointer no longer trails over the canvas (#444), artboards copied and pasted with their art (#446), guides dragged out of the rulers snapping to the art's side midpoints and the artboards, artboard guides (#451), the toolbar's double arrow and Window › Toolbars › Double Column switching between one and two columns in any window height (#455), the Smart Guides display options and Snapping Tolerance (#394), Font Size and Leading combo boxes with preset lists in the Character and Properties panels and the Control bar (#458), screenshots pasted from the clipboard on macOS, Windows and the web (#457), the Properties panel's Fill and Stroke matching the Control bar's, Illustrator's Window menu panel keys (Shift+F7 for Align…) and Alt-wheel zoom whatever the wheel preference (Discord feedback), the point/area type widget (Discord feedback), groups in legacy Illustrator .ai files (Discord feedback), a rotating desktop log file (#465), image controls in the Control bar and Properties panel: Image Trace with its presets, Mask, Crop Image, Embed/Unembed, and an Image Trace object's preset, Expand and Release (Discord feedback), the Pen working as the Anchor Point tool with Alt held over a selected path's handles and anchors, and anchor buttons that convert, connect and cut paths at the selected anchors (Discord feedback), Japanese hanging punctuation (burasagari, #463), Escape leaving Presentation Mode with no screen mode saved across restarts, documents dropped on the desktop app opening as tabs of their own and a note that an `.ai` file's art off its artboards isn't in the part read (#472), Add/Delete Anchor Point tool icons drawn from the Pen tool's (#479), EPS import running more of PostScript Level 3 (patterns, Type 3 fonts, mesh shadings, masked images, VM and resource probes), and a preview that stands in saying why (Discord feedback, #466, #469, #474), chords with modifiers recorded in Edit › Keyboard Shortcuts (#487), Type Object Selection by Path Only (#394), Anti-aliased Artwork (#394), Show Pixel Grid (#394), pen and touch taps pressed and lifted within one frame clicking where they tapped and the Linux/Wayland pen-tablet workaround (#491), bounding-box resizes landing on the other objects' anchors and centres with labels, and the Rotate, Scale, Shear and Reflect tools snapping their drags (#482), Shift-drag marquees that toggle the objects or anchors they reach and a Lasso whose Alt subtraction keeps the rest of the selection (#483), the mouse wheel stepping the focused numeric field, the dialogs' and preferences' drag values made such fields (#485), Show The Home Screen When No Documents Are Open (#394), Numbers Without Units Are Points (#394), Auto-Collapse Iconic Panels (#394), the Contextual Task Bar moved by its handle and its More Options menu pinning and resetting its position, a designed macOS DMG window (#493), panels, panel groups and the Tools panel undocking into flLine truncated
 
 ## Where we are
 

crates/engine/src/cmd/object.rs

@@ -159,7 +159,7 @@ pub fn specs() -> Vec<CommandSpec> {
             "Align",
             ["Window", "Align"],
             None,
-            "{horizontal?: \"left\"|\"center\"|\"right\", vertical?: \"top\"|\"center\"|\"bottom\", to?: \"selection\"|\"artboard\"|\"key\", bounds?: \"preview\"|\"geometric\" (default: the Use Preview Bounds preference; preview bounds take in strokes)}",
+            "{horizontal?: \"left\"|\"center\"|\"right\", vertical?: \"top\"|\"center\"|\"bottom\", to?: \"selection\"|\"artboard\"|\"key\" (default: the key object when the selection has one, select.key, else the selection), bounds?: \"preview\"|\"geometric\" (default: the Use Preview Bounds preference; preview bounds take in strokes)}",
             has_selection,
             align
         ),
@@ -177,7 +177,7 @@ pub fn specs() -> Vec<CommandSpec> {
             "Distribute Spacing",
             ["Window", "Align"],
             None,
-            "{axis: \"horizontal\"|\"vertical\", spacing?: pt, bounds?: \"preview\"|\"geometric\" (default: the Use Preview Bounds preference; preview bounds take in strokes)}",
+            "{axis: \"horizontal\"|\"vertical\", spacing?: pt (the key object, select.key, stays put and the others are spaced from it), bounds?: \"preview\"|\"geometric\" (default: the Use Preview Bounds preference; preview bounds take in strokes)}",
             has_multi,
             distribute_spacing
         ),
@@ -813,9 +813,15 @@ fn items_bounds(d: &Document, ids: &[NodeId], preview: bool) -> Vec<(NodeId, Rec
     ids.iter().filter_map(|id| Some((*id, d.bounds_of(&[*id], preview)?))).collect()
 }
 
+/// What `object.align` aligns to: `to`, else the key object when there is one, else the
+/// selection.
+fn align_to<'a>(s: &Session, p: &'a Value) -> Option<&'a str> {
+    str_param(p, "to").or_else(|| s.doc().ok()?.selection.key.map(|_| "key"))
+}
+
 fn reference_rect(s: &Session, p: &Value, ids: &[NodeId], preview: bool) -> Result<Rect> {
     let st = s.doc()?;
-    match str_param(p, "to") {
+    match align_to(s, p) {
         Some("artboard") => {
             let b = st.doc.bounds_of(ids, preview).unwrap_or_default();
             let i = st.doc.artboard_at(b.center()).unwrap_or(0);
@@ -840,7 +846,7 @@ fn align(s: &mut Session, p: &Value) -> Result<Value> {
         let d = &s.doc()?.doc;
         items_bounds(d, &ids, preview)
             .into_iter()
-            .filter(|(id, _)| Some(*id) != key || str_param(p, "to") != Some("key"))
+            .filter(|(id, _)| Some(*id) != key || align_to(s, p) != Some("key"))
             .map(|(id, b)| {
                 let dx = match h {
                     Some("left") => r.x0 - b.x0,
@@ -926,22 +932,31 @@ fn distribute_spacing(s: &mut Session, p: &Value) -> Result<Value> {
     let mut items = items_bounds(&s.doc()?.doc, &ids, preview);
     items.sort_by(|a, b| if horiz { a.1.x0.total_cmp(&b.1.x0) } else { a.1.y0.total_cmp(&b.1.y0) });
     let n = items.len();
+    let &[(_, first), .., (_, last)] = items.as_slice() else {
+        return Err(EngineError::Other("select two or more objects to distribute".into()));
+    };
     let size = |r: &Rect| if horiz { r.width() } else { r.height() };
     let start = |r: &Rect| if horiz { r.x0 } else { r.y0 };
-    let gap = match p.get("spacing").and_then(Value::as_f64) {
+    let spacing = p.get("spacing").and_then(Value::as_f64).filter(|g| g.is_finite());
+    let gap = match spacing {
         Some(g) => g,
         None => {
-            let span = if horiz { items[n - 1].1.x1 - items[0].1.x0 } else { items[n - 1].1.y1 - items[0].1.y0 };
+            let span = if horiz { last.x1 - first.x0 } else { last.y1 - first.y0 };
             (span - items.iter().map(|i| size(&i.1)).sum::<f64>()) / (n - 1) as f64
         }
     };
-    let mut pos = start(&items[0].1);
-    let mut moves = vec![];
+    let mut pos = start(&first);
+    let mut deltas = vec![];
     for (id, r) in &items {
-        let delta = pos - start(r);
-        moves.push((*id, if horiz { Vec2::new(delta, 0.0) } else { Vec2::new(0.0, delta) }));
+        deltas.push((*id, pos - start(r)));
         pos += size(r) + gap;
     }
+    // With a spacing (aligning to a key object) the key object stays where it is: the others
+    // are spaced from it.
+    let key = s.doc()?.selection.key;
+    let fixed = spacing.and_then(|_| deltas.iter().find(|(id, _)| Some(*id) == key)).map_or(0.0, |k| k.1);
+    let moves: Vec<(NodeId, Vec2)> =
+        deltas.into_iter().map(|(id, d)| (id, if horiz { Vec2::new(d - fixed, 0.0) } else { Vec2::new(0.0, d - fixed) })).collect();
     s.edit("Distribute Spacing", |d, _| {
         for (id, dv) in &moves {
             if let Some(n) = d.node_mut(*id) {

crates/engine/src/cmd/select.rs

@@ -36,7 +36,15 @@ pub fn specs() -> Vec<CommandSpec> {
             has_doc,
             toggle
         ),
-        cmd!("select.key", "Set Key Object", [], None, "{id?} (none clears)", has_doc, key),
+        cmd!(
+            "select.key",
+            "Set Key Object",
+            [],
+            None,
+            "{id?: a selected object (the Selection tool: a click on one object of a selection of several; on the key again: none)} the key object Align aligns to and Distribute Spacing spaces from; none clears it",
+            has_doc,
+            key
+        ),
         cmd!("select.anchors", "Select Anchors", [], None, "{id, anchors: [[subpath, anchor]…], mode: \"set\"|\"add\"|\"toggle\"}", has_doc, anchors),
         cmd!(
             "select.anchorsMany",

crates/engine/src/tests.rs

@@ -198,6 +198,37 @@ fn align_left() {
     assert_eq!(s.doc().unwrap().doc.node(b).unwrap().geometric_bounds().unwrap().x0, 0.0);
 }
 
+/// #541: with the Selection tool, a click on one object of the selection makes it the key object:
+/// aligning to the key moves the others to it, Distribute Spacing spaces them from it, and a click
+/// on the key again lets it go.
+#[test]
+fn a_click_sets_the_key_object_that_align_and_spacing_keep_still() {
+    let mut s = session();
+    let a = rect(&mut s, 0.0, 0.0, 10.0, 10.0);
+    let b = rect(&mut s, 100.0, 30.0, 20.0, 20.0);
+    let c = rect(&mut s, 300.0, 60.0, 10.0, 10.0);
+    s.execute("select.set", &json!({"ids": [a.0, b.0, c.0]})).unwrap();
+    let v = ViewInfo::default();
+    s.select_tool("selection", v).unwrap();
+    let click = |s: &mut Session| {
+        for kind in [PointerKind::Down, PointerKind::Up] {
+            s.pointer(&PointerEvent::new(kind, 110.0, 40.0), v).unwrap();
+        }
+    };
+    click(&mut s);
+    assert_eq!(s.doc().unwrap().selection.key, Some(b));
+    assert_eq!(s.doc().unwrap().selection.objects.len(), 3, "the selection stays");
+    let x0 = |s: &Session, id| s.doc().unwrap().doc.node(id).unwrap().geometric_bounds().unwrap().x0;
+    // With a key object, aligning aligns to it (the Control bar and Properties name no target).
+    s.execute("object.align", &json!({"horizontal": "left", "bounds": "geometric"})).unwrap();
+    assert_eq!((x0(&s, a), x0(&s, b), x0(&s, c)), (100.0, 100.0, 100.0), "the others moved to the key");
+    s.execute("edit.undo", &json!({})).unwrap();
+    s.execute("object.distributeSpacing", &json!({"axis": "horizontal", "spacing": 5, "bounds": "geometric"})).unwrap();
+    assert_eq!((x0(&s, a), x0(&s, b), x0(&s, c)), (85.0, 100.0, 125.0), "5 pt apart, the key still");
+    click(&mut s);
+    assert_eq!(s.doc().unwrap().selection.key, None, "a click on the key again lets it go");
+}
+
 #[test]
 fn selection_tool_drag_is_one_undo_step() {
     let mut s = session();

crates/tools/src/select.rs

@@ -36,6 +36,9 @@ enum State {
         /// Shift-pressed on this selected object: released without a drag, it leaves the
         /// selection.
         deselect: Option<NodeId>,
+        /// Pressed (no modifier) on this object of a selection of several: released without a
+        /// drag, it becomes the key object that Align aligns to (the key again: no key).
+        key: Option<NodeId>,
     },
     Scaling {
         handle: Handle,
@@ -235,14 +238,14 @@ impl Tool for SelectionTool {
                     && cx.select_behind
                     && let Some(behind) = object_behind(cx, p)
                 {
-                    self.state = State::Moving { start: p, began: false, deselect: None };
+                    self.state = State::Moving { start: p, began: false, deselect: None, key: None };
                     return vec![Action::Exec("select.set".into(), json!({ "ids": [behind.0] }))];
                 }
                 match hit_test(cx.doc, p, cx.hit_options()) {
                     Some(h) => {
                         let top = h.top_object(cx.isolation);
                         let mut out = vec![];
-                        let mut deselect = None;
+                        let (mut deselect, mut key) = (None, None);
                         if m.shift {
                             // A Shift-click takes a selected object out of the selection when it
                             // is released; a Shift-drag moves the selection, constrained.
@@ -253,8 +256,10 @@ impl Tool for SelectionTool {
                             }
                         } else if !cx.selection.contains(top) {
                             out.push(Action::Exec("select.set".into(), json!({ "ids": [top.0] })));
+                        } else if cx.selection.objects.len() > 1 && !m.cmd && !m.alt {
+                            key = Some(top);
                         }
-                        self.state = State::Moving { start: p, began: false, deselect };
+                        self.state = State::Moving { start: p, began: false, deselect, key };
                         out
                     }
                     None => {
@@ -276,7 +281,7 @@ impl Tool for SelectionTool {
                 if let Some(snap) = &self.moving {
                     (d, self.guides) = snap.snap(cx, start, d);
                 }
-                self.state = State::Moving { start, began: true, deselect: None };
+                self.state = State::Moving { start, began: true, deselect: None, key: None };
                 self.measure = cx.measurement_labels.then(|| (p, cx.offset_label(d.x, d.y)));
                 out.push(Action::Preview("object.transform".into(), json!({ "matrix": matrix_json(Affine::translate(d)), "copy": m.alt })));
                 out
@@ -323,15 +328,18 @@ impl Tool for SelectionTool {
                 self.state = State::Idle;
                 b.finish()
             }
-            (PointerKind::Up, State::Moving { began, deselect, .. }) => {
+            (PointerKind::Up, State::Moving { began, deselect, key, .. }) => {
                 self.state = State::Idle;
                 self.measure = None;
                 self.guides.clear();
                 self.moving = None;
-                match (began, deselect) {
-                    (true, _) => vec![Action::Commit],
-                    (false, Some(id)) => vec![Action::Exec("select.toggle".into(), json!({ "id": id.0 }))],
-                    (false, None) => vec![],
+                match (began, deselect, key) {
+                    (true, ..) => vec![Action::Commit],
+                    (false, Some(id), _) => vec![Action::Exec("select.toggle".into(), json!({ "id": id.0 }))],
+                    // A click on the key object again: no key.
+                    (false, None, Some(id)) if cx.selection.key == Some(id) => vec![Action::Exec("select.key".into(), json!({}))],
+                    (false, None, Some(id)) => vec![Action::Exec("select.key".into(), json!({ "id": id.0 }))],
+                    (false, None, None) => vec![],
                 }
             }
             (PointerKind::Up, State::Scaling { .. } | State::Rotating { .. }) => {
@@ -540,6 +548,37 @@ mod tests {
         assert!(t.pointer(&cx2, &shift(PointerKind::Up, 150.0, 150.0)).is_empty());
     }
 
+    /// #541: a click on one object of a selection of several makes it the key object; a click on
+    /// the key again lets it go. A drag moves them all, a lone object has no key.
+    #[test]
+    fn a_click_on_a_selected_object_makes_it_the_key() {
+        let (d, id) = doc_with_area_type();
+        let rect = d.layers[0].children().and_then(|c| c.first()).map(|n| n.id).unwrap();
+        let p = paint();
+        let click = |s: &Selection, x, y| {
+            let c = cx(&d, s, &p);
+            let mut t = SelectionTool::default();
+            assert!(t.pointer(&c, &ev(PointerKind::Down, x, y)).is_empty());
+            t.pointer(&c, &ev(PointerKind::Up, x, y))
+        };
+        let mut s = Selection::default();
+        s.add(rect);
+        s.add(id);
+        assert_eq!(click(&s, 150.0, 150.0), vec![Action::Exec("select.key".into(), json!({"id": rect.0}))]);
+        s.key = Some(rect);
+        assert_eq!(click(&s, 150.0, 150.0), vec![Action::Exec("select.key".into(), json!({}))], "the key again: no key");
+        // A drag moves the selection and leaves the key alone.
+        let c = cx(&d, &s, &p);
+        let mut t = SelectionTool::default();
+        t.pointer(&c, &ev(PointerKind::Down, 150.0, 150.0));
+        t.pointer(&c, &ev(PointerKind::Drag, 170.0, 150.0));
+        assert_eq!(t.pointer(&c, &ev(PointerKind::Up, 170.0, 150.0)), vec![Action::Commit]);
+        // One object selected: a click on it does nothing.
+        let mut one = Selection::default();
+        one.add(rect);
+        assert!(click(&one, 150.0, 150.0).is_empty());
+    }
+
     #[test]
     fn marquee_selects() {
         let (d, id) = doc_with_rect();

crates/ui-egui/src/canvas.rs

@@ -1041,6 +1041,9 @@ fn node_outline(n: &Node) -> BezPath {
     bp
 }
 
+/// The width of the key object's outline (Align to Key Object), thicker than the selection's.
+const KEY_OUTLINE: f32 = 2.5;
+
 /// The most anchor points the selection's outlines and anchors, and the hover highlight, are drawn
 /// for: an Image Trace of a photo selects hundreds of thousands of paths at once, whose outlines
 /// would make a mesh larger than the GPU takes in one buffer (#525).
@@ -1391,6 +1394,18 @@ fn selection_overlay(app: &mut VectorcraftApp, p: &egui::Painter, xf: &Xf) {
     if let Some((b, id)) = big_bounds.zip(st.selection.objects.first()) {
         stroke_path(p, &vectorcraft_geom::shapes::rectangle(b).to_bezpath(), xf, Stroke::new(1.0, c32(st.doc.layer_color(*id))));
     }
+    // The key object (Align to Key Object): its outline drawn thicker, or its bounds when it has
+    // too many paths to outline.
+    if let Some((k, n)) = st.selection.key.and_then(|k| Some((k, st.doc.node(k)?))) {
+        let outline = if too_many_anchors([n]) {
+            n.geometric_bounds().map(|b| vectorcraft_geom::shapes::rectangle(b).to_bezpath())
+        } else {
+            Some(node_outline(n))
+        };
+        if let Some(bp) = outline {
+            stroke_path(p, &bp, xf, Stroke::new(KEY_OUTLINE, c32(st.doc.layer_color(k))));
+        }
+    }
     for id in st.selection.objects.iter().filter(|_| !big) {
         let Some(n) = st.doc.node(*id) else { continue };
         let color = c32(st.doc.layer_color(*id));
@@ -2077,6 +2092,23 @@ mod tests {
         assert!(points > 200 && squares > 200, "{points} outline points, {squares} squares");
     }
 
+    /// #541: the key object's outline is drawn thicker than the rest of the selection's.
+    #[test]
+    fn the_key_object_has_a_thicker_outline() {
+        let mut app = VectorcraftApp::new(Session::new(), Default::default());
+        app.session.execute("file.new", &json!({"width": 400, "height": 300})).unwrap();
+        let a = app.session.execute("shape.rectangle", &json!({"x": 20, "y": 20, "width": 50, "height": 50})).unwrap()["id"].clone();
+        let b = app.session.execute("shape.ellipse", &json!({"x": 200, "y": 100, "width": 60, "height": 40})).unwrap()["id"].clone();
+        app.session.execute("select.set", &json!({"ids": [a, b]})).unwrap();
+        let ctx = egui::Context::default();
+        frame(&mut app, &ctx, vec![]);
+        let thick =
+            |app: &mut VectorcraftApp| shapes(app, &ctx).iter().filter(|s| matches!(s, Shape::Path(ps) if ps.stroke.width == KEY_OUTLINE)).count();
+        assert_eq!(thick(&mut app), 0, "no key yet");
+        app.session.execute("select.key", &json!({"id": b})).unwrap();
+        assert!(thick(&mut app) > 0, "the key's outline");
+    }
+
     /// One headless canvas frame → the shapes drawn, `Shape::Vec`s flattened.
     fn shapes(app: &mut VectorcraftApp, ctx: &egui::Context) -> Vec<Shape> {
         let (shapes, mut delta) = frame_output(app, ctx);

crates/ui-egui/src/i18n/es.tsv

@@ -3117,6 +3117,7 @@ axis	Both	Ambos
 @msg	Release Guides: no guides	Soltar guías: no hay guías
 @msg	Release: no layer to put the rectangle in	Soltar: no hay ninguna capa donde poner el rectángulo
 @msg	Replace Spine: select a blend and a path	Reemplazar eje: selecciona una fusión y un trazado
+@msg	select two or more objects to distribute	selecciona dos o más objetos para distribuir
 @msg	select paths or anchor points	selecciona trazados o puntos de ancla
 @msg	SVG parse error: {0}	error al analizar el SVG: {0}
 @msg	Save for Web: the image is empty	Guardar para web: la imagen está vacía

crates/ui-egui/src/i18n/it.tsv

@@ -3117,6 +3117,7 @@ axis	Both	Entrambi
 @msg	Release Guides: no guides	Rilascia guide: nessuna guida
 @msg	Release: no layer to put the rectangle in	Rilascia: nessun livello in cui inserire il rettangolo
 @msg	Replace Spine: select a blend and a path	Sostituisci dorsale: seleziona una fusione e un tracciato
+@msg	select two or more objects to distribute	seleziona due o più oggetti da distribuire
 @msg	select paths or anchor points	seleziona tracciati o punti di ancoraggio
 @msg	SVG parse error: {0}	Errore di analisi SVG: {0}
 @msg	Save for Web: the image is empty	Salva per il web: l'immagine è vuota

crates/ui-egui/src/panels/align.rs

@@ -52,9 +52,20 @@ pub const DISTRIBUTE: [(&str, &str, &str, &str); 6] = [
     ("dc-dist-right", "Horizontal Distribute Right", "horizontal", "right"),
 ];
 
+/// Whether the selection has a key object.
+fn has_key(app: &VectorcraftApp) -> bool {
+    app.session.active().is_some_and(|st| st.selection.key.is_some())
+}
+
+/// What Align aligns to: the key object while there is one (a click on an object of the
+/// selection makes it the key), else the Align To choice.
+fn align_to(app: &VectorcraftApp, ctx: &egui::Context) -> AlignTo {
+    if has_key(app) { AlignTo::Key } else { pstate(ctx, "align-to") }
+}
+
 pub fn show(app: &mut VectorcraftApp, ui: &mut Ui) {
     let n = selection_len(app);
-    let to: AlignTo = pstate(ui.ctx(), "align-to");
+    let to = align_to(app, ui.ctx());
     widgets::subheader(ui, tl!("Align Objects:"));
     ui.horizontal(|ui| {
         ui.spacing_mut().item_spacing.x = 5.0;
@@ -116,6 +127,10 @@ pub fn show(app: &mut VectorcraftApp, ui: &mut Ui) {
                 ] {
                     if widgets::icon_button(ui, icon, tl!(tip), to == v, 28.0).clicked() {
                         set_pstate(ui.ctx(), "align-to", v);
+                        // Aligning to the selection or the artboard lets go of the key object.
+                        if v != AlignTo::Key && has_key(app) {
+                            app.run("select.key", json!({})).ok();
+                        }
                     }
                 }
             });
@@ -132,8 +147,7 @@ pub fn menu(app: &mut VectorcraftApp, ui: &mut Ui) {
     if menu_item(ui, tl!("Use Preview Bounds"), true, pb) {
         super::transform::set_pref(app, "usePreviewBounds", !pb);
     }
-    let to: AlignTo = pstate(ui.ctx(), "align-to");
-    if menu_item(ui, tl!("Cancel Key Object"), to == AlignTo::Key, false) {
+    if menu_item(ui, tl!("Cancel Key Object"), align_to(app, ui.ctx()) == AlignTo::Key, false) {
         set_pstate(ui.ctx(), "align-to", AlignTo::Selection);
         app.run("select.key", json!({})).ok();
     }
@@ -152,4 +166,21 @@ mod tests {
         assert_eq!(p["to"], "selection");
         assert_eq!(align_params(json!({}), AlignTo::Key, 1)["to"], "key");
     }
+
+    /// #541: while the selection has a key object Align aligns to it, whatever Align To says;
+    /// choosing Align to Selection lets the key go.
+    #[test]
+    fn a_key_object_makes_align_align_to_it() {
+        let mut app = VectorcraftApp::new(vectorcraft_engine::Session::new(), Default::default());
+        app.run("file.new", json!({"width": 200, "height": 200})).unwrap();
+        let a = app.run("shape.rectangle", json!({"x": 10, "y": 10, "width": 10, "height": 10})).unwrap()["id"].clone();
+        let b = app.run("shape.rectangle", json!({"x": 80, "y": 50, "width": 30, "height": 30})).unwrap()["id"].clone();
+        app.run("select.set", json!({"ids": [a, b]})).unwrap();
+        let ctx = egui::Context::default();
+        assert_eq!(align_to(&app, &ctx), AlignTo::Selection);
+        app.run("select.key", json!({"id": b})).unwrap();
+        assert_eq!(align_to(&app, &ctx), AlignTo::Key);
+        app.run("select.key", json!({})).unwrap();
+        assert_eq!(align_to(&app, &ctx), AlignTo::Selection, "no key: the choice again");
+    }
 }