Fix #649: a panel dropped on the dock lights up where it goes

Panels other than Properties, Layers and Libraries live in the dock's icon
column, not as tabs. Dragging one onto the dock lit up the whole dock, tabs
included, and the drop put it back as an icon, so it seemed to vanish. The
drop zone now lights up the icon column for such panels (the whole dock still
for the tabbed ones), and the dropped panel pops out of its icon.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

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 placed documents (File › Place of a `.vectorcraft` file, linked), 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 windoLine truncated
+_Last updated: 2026-10-09 (after placed documents (File › Place of a `.vectorcraft` file, linked), 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 windoLine truncated
 
 ## Where we are
 

crates/ui-egui/src/dock.rs

@@ -151,6 +151,7 @@ pub fn show(app: &mut VectorcraftApp, ui: &mut Ui) {
     ui.ctx().data_mut(|d| {
         d.insert_temp(column_left_id(), column.left());
         d.insert_temp(floating::dock_rect_id(), dock);
+        d.insert_temp(floating::icons_rect_id(), column);
     });
 }
 

crates/ui-egui/src/floating.rs

@@ -70,6 +70,12 @@ pub(crate) fn dock_rect_id() -> Id {
 }
 
 /// The strip along the window's left edge where the Tools panel docks, as last laid out.
+/// The icon column's bounds (egui temp memory, one frame old), where panels without a tab in the
+/// tabbed group go back to when docked.
+pub(crate) fn icons_rect_id() -> Id {
+    Id::new("floating-icons-rect")
+}
+
 pub(crate) fn tools_zone_id() -> Id {
     Id::new("floating-tools-zone")
 }
@@ -216,7 +222,13 @@ fn drop_target(app: &VectorcraftApp, ctx: &egui::Context, what: Moving, at: Pos2
             return Some((Drop::Stack(first), head));
         }
     }
-    zone(dock_rect_id()).filter(|_| app.ui.dock && app.ui.screen_mode < 3).map(|r| (Drop::Dock, r))
+    let dock = zone(dock_rect_id()).filter(|_| app.ui.dock && app.ui.screen_mode < 3)?;
+    // Panels that aren't tabs of the tabbed group (or all of them, with it collapsed) go back to
+    // their icons: light up the icon column, where they land, rather than the tabs.
+    let tabbed = !app.ui.dock_collapsed
+        && own.and_then(|i| app.ui.floating_panels.get(i)).is_some_and(|g| ids_of(g).into_iter().any(|p| DockTab::from_id(p).is_some()));
+    let lit = if tabbed { dock } else { ctx.data(|d| d.get_temp::<Rect>(icons_rect_id())).unwrap_or(dock) };
+    Some((Drop::Dock, lit))
 }
 
 /// Light up a drop zone: over the docked panels, under the floating ones (the moved one too).
@@ -262,7 +274,13 @@ pub fn track(app: &mut VectorcraftApp, ctx: &egui::Context) {
     let ids = ids_of(g);
     let active = ids.get(g.active).copied().unwrap_or(id);
     match drop {
-        Drop::Dock => dock(&mut app.ui, &ids, active),
+        Drop::Dock => {
+            dock(&mut app.ui, &ids, active);
+            // One that went back to its icon pops out of it, so it doesn't seem to vanish.
+            if app.ui.dock_collapsed || DockTab::from_id(active).is_none() {
+                app.ui.open_panel = Some(active.to_string());
+            }
+        }
         Drop::Stack(onto) => stack(&mut app.ui, &ids, active, onto),
     }
 }
@@ -607,7 +625,7 @@ mod tests {
         h.hold(h.title("layers"), over);
         assert!(h.group("layers").contains(over), "the group follows the pointer");
         let target = drop_target(&h.app, &h.ctx, Moving::Panel("layers"), over);
-        assert_eq!(target.map(|t| t.0), Some(Drop::Dock), "the dock is the drop zone");
+        assert_eq!(target, Some((Drop::Dock, dock)), "the dock is the drop zone, lit whole: its tab comes back");
         h.release(over);
         assert!(h.groups().is_empty(), "docked: {:?}", h.groups());
         assert_eq!((h.dock_tabs().len(), h.app.ui.dock_tab), (3, DockTab::Layers), "back in the dock, shown");
@@ -666,6 +684,24 @@ mod tests {
         assert_eq!(h.icons().len(), count - 1, "Color is back in the column");
     }
 
+    #[test]
+    fn a_panel_dropped_on_the_dock_lights_up_and_pops_out_of_its_icon() {
+        let mut h = Harness::new();
+        let count = h.icons().len();
+        h.drag(h.icons()[0].center(), pos2(500.0, 400.0));
+        assert_eq!(h.groups(), [["color"]]);
+        // Over the tabbed group: Color has no tab there, so the icon column lights up, not the tabs.
+        let (dock, column) = (h.temp_rect(dock_rect_id()), h.temp_rect(icons_rect_id()));
+        let over = h.dock_tabs()[1].center();
+        h.hold(h.title("color"), over);
+        assert_eq!(drop_target(&h.app, &h.ctx, Moving::Panel("color"), over), Some((Drop::Dock, column)));
+        assert!(column.width() < dock.width(), "the column, not the whole dock: {column:?} {dock:?}");
+        // Dropped, it's back in the column and pops out of its icon rather than vanishing.
+        h.release(over);
+        assert!(h.groups().is_empty());
+        assert_eq!((h.icons().len(), h.app.ui.open_panel.as_deref()), (count, Some("color")));
+    }
+
     #[test]
     fn a_popped_out_panel_dragged_by_its_title_floats() {
         let mut h = Harness::new();