tree: implement tile dragging

src/gfx_api.rs

@@ -722,6 +722,9 @@ pub fn create_render_pass(
                     }
                 }
             }
+            if let Some(highlight) = seat.ui_drag_highlight() {
+                renderer.render_highlight(&highlight.move_(-rect.x1(), -rect.y1()));
+            }
             if let Some(drag) = seat.toplevel_drag() {
                 drag.render(&mut renderer, &rect, x, y);
             }

src/ifs/wl_seat.rs

@@ -171,6 +171,7 @@ pub struct WlSeatGlobal {
     cursor_user_group: Rc<CursorUserGroup>,
     pointer_cursor: Rc<CursorUser>,
     tree_changed: Rc<AsyncEvent>,
+    tree_changed_needs_layout: Cell<bool>,
     selection: CloneCell<Option<Rc<dyn DynDataSource>>>,
     selection_serial: Cell<u32>,
     primary_selection: CloneCell<Option<Rc<dyn DynDataSource>>>,
@@ -198,6 +199,7 @@ pub struct WlSeatGlobal {
     hold_bindings: PerClientBindings<ZwpPointerGestureHoldV1>,
     tablet: TabletSeatData,
     ei_seats: CopyHashMap<(ClientId, EiSeatId), Rc<EiSeat>>,
+    ui_drag_highlight: Cell<Option<Rect>>,
 }
 
 const CHANGE_CURSOR_MOVED: u32 = 1 << 0;
@@ -239,6 +241,7 @@ impl WlSeatGlobal {
             cursor_user_group,
             pointer_cursor: cursor_user,
             tree_changed: Default::default(),
+            tree_changed_needs_layout: Default::default(),
             selection: Default::default(),
             selection_serial: Cell::new(0),
             primary_selection: Default::default(),
@@ -267,12 +270,16 @@ impl WlSeatGlobal {
             hold_bindings: Default::default(),
             tablet: Default::default(),
             ei_seats: Default::default(),
+            ui_drag_highlight: Default::default(),
         });
         slf.pointer_cursor.set_owner(slf.clone());
         let seat = slf.clone();
         let future = state.eng.spawn("seat handler", async move {
             loop {
                 seat.tree_changed.triggered().await;
+                if seat.tree_changed_needs_layout.take() {
+                    seat.state.eng.yield_now().await;
+                }
                 seat.state.tree_changed_sent.set(false);
                 seat.changes.or_assign(CHANGE_TREE);
                 // log::info!("tree_changed");
@@ -314,6 +321,10 @@ impl WlSeatGlobal {
         self.pointer_owner.toplevel_drag()
     }
 
+    pub fn ui_drag_highlight(&self) -> Option<Rect> {
+        self.ui_drag_highlight.get()
+    }
+
     pub fn add_data_device(&self, device: &Rc<WlDataDevice>) {
         let mut dd = self.data_devices.borrow_mut();
         dd.entry(device.client.id)
@@ -764,6 +775,10 @@ impl WlSeatGlobal {
             .start_drag(self, origin, source, icon, serial)
     }
 
+    pub fn start_tile_drag(self: &Rc<Self>, tl: &Rc<dyn ToplevelNode>) {
+        self.pointer_owner.start_tile_drag(self, tl);
+    }
+
     pub fn cancel_dnd(self: &Rc<Self>) {
         self.pointer_owner.cancel_dnd(self);
     }

src/ifs/wl_seat/event_handling.rs

@@ -64,6 +64,7 @@ pub struct NodeSeatState {
     dnd_targets: SmallMap<SeatId, Rc<WlSeatGlobal>, 1>,
     tablet_pad_foci: SmallMap<TabletPadId, Rc<TabletPad>, 1>,
     tablet_tool_foci: SmallMap<TabletToolId, Rc<TabletTool>, 1>,
+    ui_drags: SmallMap<SeatId, Rc<WlSeatGlobal>, 1>,
 }
 
 impl NodeSeatState {
@@ -101,6 +102,14 @@ impl NodeSeatState {
         self.pointer_grabs.remove(&seat.id);
     }
 
+    pub(super) fn add_ui_drag(&self, seat: &Rc<WlSeatGlobal>) {
+        self.ui_drags.insert(seat.id, seat.clone());
+    }
+
+    pub(super) fn remove_ui_drag(&self, seat: &WlSeatGlobal) {
+        self.ui_drags.remove(&seat.id);
+    }
+
     pub(super) fn add_tablet_pad_focus(&self, pad: &Rc<TabletPad>) {
         self.tablet_pad_foci.insert(pad.id, pad.clone());
     }
@@ -176,6 +185,9 @@ impl NodeSeatState {
         while let Some((_, seat)) = self.pointer_grabs.pop() {
             seat.pointer_owner.grab_node_removed(&seat);
         }
+        while let Some((_, seat)) = self.ui_drags.pop() {
+            seat.pointer_owner.revert_to_default(&seat);
+        }
         let node_id = node.node_id();
         while let Some((_, seat)) = self.dnd_targets.pop() {
             seat.pointer_owner.dnd_target_removed(&seat);
@@ -1100,8 +1112,11 @@ impl WlSeatGlobal {
         }
     }
 
-    pub fn trigger_tree_changed(&self) {
+    pub fn trigger_tree_changed(&self, needs_layout: bool) {
         // log::info!("trigger_tree_changed");
+        if needs_layout {
+            self.tree_changed_needs_layout.set(true);
+        }
         self.tree_changed.trigger();
     }
 

src/ifs/wl_seat/pointer_owner.rs

@@ -7,13 +7,17 @@ use {
             ipc,
             ipc::wl_data_source::WlDataSource,
             wl_seat::{
-                wl_pointer::PendingScroll, Dnd, DroppedDnd, WlSeatError, WlSeatGlobal, BTN_LEFT,
+                wl_pointer::PendingScroll, Dnd, DroppedDnd, NodeSeatState, WlSeatError,
-                BTN_RIGHT, CHANGE_CURSOR_MOVED, CHANGE_TREE,
+                WlSeatGlobal, BTN_LEFT, BTN_RIGHT, CHANGE_CURSOR_MOVED, CHANGE_TREE,
             },
             wl_surface::{dnd_icon::DndIcon, WlSurface},
             xdg_toplevel_drag_v1::XdgToplevelDragV1,
         },
-        tree::{ContainingNode, FindTreeUsecase, FoundNode, Node, ToplevelNode, WorkspaceNode},
+        rect::Rect,
+        tree::{
+            ContainerNode, ContainerSplit, ContainingNode, FindTreeUsecase, FoundNode, Node,
+            PlaceholderNode, TddType, ToplevelNode, WorkspaceNode,
+        },
         utils::{clonecell::CloneCell, smallmap::SmallMap},
     },
     std::{
@@ -173,7 +177,7 @@ impl PointerOwnerHolder {
             usecase.node_focus(seat, node);
         }
         self.owner.set(Rc::new(SimplePointerOwner { usecase }));
-        seat.trigger_tree_changed();
+        seat.trigger_tree_changed(false);
     }
 
     pub fn select_toplevel(&self, seat: &Rc<WlSeatGlobal>, selector: impl ToplevelSelector) {
@@ -202,11 +206,18 @@ impl PointerOwnerHolder {
             owner.disable_window_management(seat);
         }
     }
+
+    pub fn start_tile_drag(&self, seat: &Rc<WlSeatGlobal>, tl: &Rc<dyn ToplevelNode>) {
+        self.owner.get().start_tile_drag(seat, tl);
+    }
 }
 
 trait PointerOwner {
     fn button(&self, seat: &Rc<WlSeatGlobal>, time_usec: u64, button: u32, state: KeyState);
-    fn axis_node(&self, seat: &Rc<WlSeatGlobal>) -> Option<Rc<dyn Node>>;
+    fn axis_node(&self, seat: &Rc<WlSeatGlobal>) -> Option<Rc<dyn Node>> {
+        let _ = seat;
+        None
+    }
     fn apply_changes(&self, seat: &Rc<WlSeatGlobal>);
     fn start_drag(
         &self,
@@ -249,6 +260,10 @@ trait PointerOwner {
     fn disable_window_management(&self, seat: &Rc<WlSeatGlobal>) {
         let _ = seat;
     }
+    fn start_tile_drag(&self, seat: &Rc<WlSeatGlobal>, tl: &Rc<dyn ToplevelNode>) {
+        let _ = seat;
+        let _ = tl;
+    }
 }
 
 struct SimplePointerOwner<T> {
@@ -386,7 +401,7 @@ impl<T: SimplePointerOwnerUsecase> PointerOwner for SimplePointerOwner<T> {
     fn revert_to_default(&self, seat: &Rc<WlSeatGlobal>) {
         if !T::IS_DEFAULT {
             seat.pointer_owner.set_default_pointer_owner(seat);
-            seat.trigger_tree_changed();
+            seat.trigger_tree_changed(false);
         }
     }
 
@@ -458,6 +473,10 @@ impl<T: SimplePointerOwnerUsecase> PointerOwner for SimpleGrabPointerOwner<T> {
         self.node.node_seat_state().remove_pointer_grab(seat);
         seat.pointer_owner.set_default_pointer_owner(seat);
     }
+
+    fn start_tile_drag(&self, seat: &Rc<WlSeatGlobal>, tl: &Rc<dyn ToplevelNode>) {
+        self.usecase.start_tile_drag(self, seat, tl);
+    }
 }
 
 impl PointerOwner for DndPointerOwner {
@@ -496,10 +515,6 @@ impl PointerOwner for DndPointerOwner {
         }
     }
 
-    fn axis_node(&self, _seat: &Rc<WlSeatGlobal>) -> Option<Rc<dyn Node>> {
-        None
-    }
-
     fn apply_changes(&self, seat: &Rc<WlSeatGlobal>) {
         let (x, y) = seat.pointer_cursor.position();
         let (x_int, y_int) = (x.round_down(), y.round_down());
@@ -620,6 +635,43 @@ trait SimplePointerOwnerUsecase: Sized + Clone + 'static {
     fn disable_window_management(&self, seat: &Rc<WlSeatGlobal>) {
         let _ = seat;
     }
+
+    fn start_tile_drag(
+        &self,
+        grab: &SimpleGrabPointerOwner<Self>,
+        seat: &Rc<WlSeatGlobal>,
+        tl: &Rc<dyn ToplevelNode>,
+    ) {
+        let _ = grab;
+        let _ = seat;
+        let _ = tl;
+    }
+}
+
+impl DefaultPointerUsecase {
+    fn prepare_new_usecase(&self, grab: &SimpleGrabPointerOwner<Self>, seat: &Rc<WlSeatGlobal>) {
+        {
+            let mut stack = seat.pointer_stack.borrow_mut();
+            for node in stack.drain(1..).rev() {
+                node.node_on_leave(seat);
+                node.node_seat_state().leave(seat);
+            }
+        }
+        grab.node.node_seat_state().remove_pointer_grab(seat);
+    }
+
+    fn start_ui_drag<T: UiDragUsecase>(
+        &self,
+        grab: &SimpleGrabPointerOwner<Self>,
+        seat: &Rc<WlSeatGlobal>,
+        usecase: T,
+    ) {
+        self.prepare_new_usecase(grab, seat);
+        usecase.node_seat_state().add_ui_drag(seat);
+        let pointer_owner = Rc::new(UiDragPointerOwner { usecase });
+        seat.pointer_owner.owner.set(pointer_owner.clone());
+        pointer_owner.apply_changes(seat);
+    }
 }
 
 impl SimplePointerOwnerUsecase for DefaultPointerUsecase {
@@ -680,14 +732,7 @@ impl SimplePointerOwnerUsecase for DefaultPointerUsecase {
             pos_x: Cell::new(Fixed::from_int(0)),
             pos_y: Cell::new(Fixed::from_int(0)),
         });
-        {
+        self.prepare_new_usecase(grab, seat);
-            let mut stack = seat.pointer_stack.borrow_mut();
-            for node in stack.drain(1..).rev() {
-                node.node_on_leave(seat);
-                node.node_seat_state().leave(seat);
-            }
-        }
-        grab.node.node_seat_state().remove_pointer_grab(seat);
         // {
         //     let old = seat.keyboard_node.set(seat.state.root.clone());
         //     old.seat_state().unfocus(seat);
@@ -701,6 +746,22 @@ impl SimplePointerOwnerUsecase for DefaultPointerUsecase {
     fn release_grab(&self, seat: &Rc<WlSeatGlobal>) {
         seat.pointer_owner.set_default_pointer_owner(seat);
     }
+
+    fn start_tile_drag(
+        &self,
+        grab: &SimpleGrabPointerOwner<Self>,
+        seat: &Rc<WlSeatGlobal>,
+        tl: &Rc<dyn ToplevelNode>,
+    ) {
+        self.start_ui_drag(
+            grab,
+            seat,
+            TileDragUsecase {
+                tl: tl.clone(),
+                destination: Default::default(),
+            },
+        );
+    }
 }
 
 trait NodeSelectorUsecase: Sized + 'static {
@@ -945,10 +1006,6 @@ where
         self.grab_node_removed(seat);
     }
 
-    fn axis_node(&self, _seat: &Rc<WlSeatGlobal>) -> Option<Rc<dyn Node>> {
-        None
-    }
-
     fn apply_changes(&self, seat: &Rc<WlSeatGlobal>) {
         let Some(parent) = self.tl.tl_data().parent.get() else {
             return;
@@ -1050,3 +1107,179 @@ impl WindowManagementGrabUsecase for ResizeToplevelGrabPointerOwner {
         }
     }
 }
+
+trait UiDragUsecase: 'static {
+    fn node_seat_state(&self) -> &NodeSeatState;
+    fn left_button_up(&self, seat: &Rc<WlSeatGlobal>);
+    fn apply_changes(&self, seat: &Rc<WlSeatGlobal>) -> Option<Rect>;
+}
+
+struct UiDragPointerOwner<T> {
+    usecase: T,
+}
+
+impl<T> UiDragPointerOwner<T>
+where
+    T: UiDragUsecase,
+{
+    fn do_revert_to_default(&self, seat: &Rc<WlSeatGlobal>, needs_layout: bool) {
+        self.usecase.node_seat_state().remove_ui_drag(seat);
+        if let Some(rect) = seat.ui_drag_highlight.take() {
+            seat.state.damage(rect);
+        }
+        seat.pointer_owner.set_default_pointer_owner(seat);
+        seat.trigger_tree_changed(needs_layout);
+    }
+}
+
+impl<T> PointerOwner for UiDragPointerOwner<T>
+where
+    T: UiDragUsecase,
+{
+    fn button(&self, seat: &Rc<WlSeatGlobal>, _time_usec: u64, button: u32, state: KeyState) {
+        if button == BTN_RIGHT {
+            self.do_revert_to_default(seat, false);
+            return;
+        }
+        if button != BTN_LEFT || state != KeyState::Released {
+            return;
+        }
+        self.apply_changes(seat);
+        self.usecase.left_button_up(seat);
+        self.do_revert_to_default(seat, true);
+    }
+
+    fn apply_changes(&self, seat: &Rc<WlSeatGlobal>) {
+        let new_highlight = self.usecase.apply_changes(seat);
+        let prev_highlight = seat.ui_drag_highlight.replace(new_highlight);
+        if prev_highlight != new_highlight {
+            if let Some(rect) = prev_highlight {
+                seat.state.damage(rect);
+            }
+            if let Some(rect) = new_highlight {
+                seat.state.damage(rect);
+            }
+        }
+    }
+
+    fn revert_to_default(&self, seat: &Rc<WlSeatGlobal>) {
+        self.do_revert_to_default(seat, false);
+    }
+}
+
+struct TileDragUsecase {
+    tl: Rc<dyn ToplevelNode>,
+    destination: Cell<Option<TddType>>,
+}
+
+impl UiDragUsecase for TileDragUsecase {
+    fn node_seat_state(&self) -> &NodeSeatState {
+        self.tl.node_seat_state()
+    }
+
+    fn left_button_up(&self, seat: &Rc<WlSeatGlobal>) {
+        let Some(dest) = self.destination.take() else {
+            return;
+        };
+        let src = self.tl.clone();
+        let Some(src_parent) = src.tl_data().parent.get() else {
+            return;
+        };
+        let detach = || {
+            let placeholder = Rc::new(PlaceholderNode::new_empty(&seat.state));
+            src_parent
+                .clone()
+                .cnode_replace_child(src.tl_as_node(), placeholder.clone());
+            placeholder
+        };
+        let new_container = |workspace: &Rc<WorkspaceNode>| {
+            src_parent
+                .clone()
+                .cnode_remove_child2(src.tl_as_node(), true);
+            let cn = ContainerNode::new(
+                &seat.state,
+                &workspace,
+                src.clone(),
+                ContainerSplit::Horizontal,
+            );
+            workspace.set_container(&cn);
+        };
+        match dest {
+            TddType::Replace(dst) => {
+                let Some(dst_parent) = dst.tl_data().parent.get() else {
+                    return;
+                };
+                let placeholder = detach();
+                dst_parent.cnode_replace_child(dst.tl_as_node(), src);
+                src_parent.cnode_replace_child(placeholder.tl_as_node(), dst);
+            }
+            TddType::Split {
+                node,
+                split,
+                before,
+            } => {
+                let data = node.tl_data();
+                let Some(pn) = data.parent.get() else {
+                    return;
+                };
+                let Some(ws) = data.workspace.get() else {
+                    return;
+                };
+                let placeholder = detach();
+                let cn = ContainerNode::new(&seat.state, &ws, node.clone(), split);
+                pn.cnode_replace_child(node.tl_as_node(), cn.clone());
+                match before {
+                    true => cn.add_child_before(node.tl_as_node(), src),
+                    false => cn.add_child_after(node.tl_as_node(), src),
+                }
+                src_parent.cnode_remove_child(placeholder.tl_as_node());
+            }
+            TddType::Insert {
+                container,
+                neighbor,
+                before,
+            } => {
+                let placeholder = detach();
+                match before {
+                    true => container.add_child_before(neighbor.tl_as_node(), src),
+                    false => container.add_child_after(neighbor.tl_as_node(), src),
+                };
+                src_parent.cnode_remove_child(placeholder.tl_as_node());
+            }
+            TddType::NewWorkspace { output } => {
+                new_container(&output.ensure_workspace());
+            }
+            TddType::NewContainer { workspace } => {
+                new_container(&workspace);
+            }
+            TddType::MoveToWorkspace { workspace } => {
+                src_parent.cnode_remove_child(src.tl_as_node());
+                seat.state.map_tiled_on(src, &workspace);
+            }
+            TddType::MoveToNewWorkspace { output } => {
+                let ws = output.generate_workspace();
+                src_parent.cnode_remove_child(src.tl_as_node());
+                seat.state.map_tiled_on(src, &ws);
+            }
+        }
+    }
+
+    fn apply_changes(&self, seat: &Rc<WlSeatGlobal>) -> Option<Rect> {
+        let (x, y) = seat.pointer_cursor.position();
+        let dest = seat.state.root.tile_drag_destination(
+            self.tl.node_id(),
+            x.round_down(),
+            y.round_down(),
+        );
+        match dest {
+            None => {
+                self.destination.take();
+                None
+            }
+            Some(d) => {
+                self.destination.set(Some(d.ty));
+                Some(d.highlight)
+            }
+        }
+    }
+}

src/ifs/wl_surface/x_surface/xwindow.rs

@@ -11,8 +11,9 @@ use {
         renderer::Renderer,
         state::State,
         tree::{
-            Direction, FindTreeResult, FindTreeUsecase, FoundNode, Node, NodeId, NodeVisitor,
+            default_tile_drag_destination, ContainerSplit, Direction, FindTreeResult,
-            StackedNode, ToplevelData, ToplevelNode, ToplevelNodeBase, WorkspaceNode,
+            FindTreeUsecase, FoundNode, Node, NodeId, NodeVisitor, StackedNode,
+            TileDragDestination, ToplevelData, ToplevelNode, ToplevelNodeBase, WorkspaceNode,
         },
         utils::{clonecell::CloneCell, copyhashmap::CopyHashMap, linkedlist::LinkedNode},
         wire::WlSurfaceId,
@@ -467,6 +468,17 @@ impl ToplevelNodeBase for Xwindow {
     fn tl_admits_children(&self) -> bool {
         false
     }
+
+    fn tl_tile_drag_destination(
+        self: Rc<Self>,
+        source: NodeId,
+        split: Option<ContainerSplit>,
+        abs_bounds: Rect,
+        abs_x: i32,
+        abs_y: i32,
+    ) -> Option<TileDragDestination> {
+        default_tile_drag_destination(self, source, split, abs_bounds, abs_x, abs_y)
+    }
 }
 
 impl StackedNode for Xwindow {

src/ifs/wl_surface/xdg_surface/xdg_toplevel.rs

@@ -25,9 +25,9 @@ use {
         renderer::Renderer,
         state::State,
         tree::{
-            Direction, FindTreeResult, FindTreeUsecase, FoundNode, Node, NodeId, NodeVisitor,
+            default_tile_drag_destination, ContainerSplit, Direction, FindTreeResult,
-            OutputNode, ToplevelData, ToplevelNode, ToplevelNodeBase, ToplevelNodeId,
+            FindTreeUsecase, FoundNode, Node, NodeId, NodeVisitor, OutputNode, TileDragDestination,
-            WorkspaceNode,
+            ToplevelData, ToplevelNode, ToplevelNodeBase, ToplevelNodeId, WorkspaceNode,
         },
         utils::{clonecell::CloneCell, hash_map_ext::HashMapExt},
         wire::{xdg_toplevel::*, XdgToplevelId},
@@ -667,6 +667,17 @@ impl ToplevelNodeBase for XdgToplevel {
     fn tl_admits_children(&self) -> bool {
         false
     }
+
+    fn tl_tile_drag_destination(
+        self: Rc<Self>,
+        source: NodeId,
+        split: Option<ContainerSplit>,
+        abs_bounds: Rect,
+        x: i32,
+        y: i32,
+    ) -> Option<TileDragDestination> {
+        default_tile_drag_destination(self, source, split, abs_bounds, x, y)
+    }
 }
 
 impl XdgSurfaceExt for XdgToplevel {

src/rect.rs

@@ -71,8 +71,13 @@ impl Rect {
         })
     }
 
+    #[track_caller]
+    pub fn new_unchecked(x1: i32, y1: i32, x2: i32, y2: i32) -> Self {
+        Self::new(x1, y1, x2, y2).unwrap()
+    }
+
     #[expect(dead_code)]
-    fn new_unchecked(x1: i32, y1: i32, x2: i32, y2: i32) -> Self {
+    fn new_unchecked_danger(x1: i32, y1: i32, x2: i32, y2: i32) -> Self {
         Self {
             raw: RectRaw { x1, y1, x2, y2 },
         }

src/rect/tests.rs

@@ -70,9 +70,9 @@ fn subtract1() {
 #[test]
 fn rects_to_bands() {
     let rects = [
-        Rect::new_unchecked(0, 0, 10, 10),
+        Rect::new_unchecked_danger(0, 0, 10, 10),
-        Rect::new_unchecked(5, 0, 30, 10),
+        Rect::new_unchecked_danger(5, 0, 30, 10),
-        Rect::new_unchecked(30, 5, 50, 15),
+        Rect::new_unchecked_danger(30, 5, 50, 15),
     ];
     let r = Region::from_rects(&rects[..]);
     // println!("{:#?}", r.rects);
@@ -104,8 +104,8 @@ fn rects_to_bands() {
 #[test]
 fn rects_to_bands2() {
     let rects = [
-        Rect::new_unchecked(0, 0, 10, 10),
+        Rect::new_unchecked_danger(0, 0, 10, 10),
-        Rect::new_unchecked(0, 10, 10, 20),
+        Rect::new_unchecked_danger(0, 10, 10, 20),
     ];
     let r = Region::from_rects(&rects[..]);
     // println!("{:#?}", r.rects);

src/renderer.rs

@@ -317,11 +317,11 @@ impl Renderer<'_> {
         render_highlight: bool,
     ) {
         if render_highlight {
-            self.render_highlight(tl_data, bounds);
+            self.render_tl_highlight(tl_data, bounds);
         }
     }
 
-    fn render_highlight(&mut self, tl_data: &ToplevelData, bounds: Option<&Rect>) {
+    fn render_tl_highlight(&mut self, tl_data: &ToplevelData, bounds: Option<&Rect>) {
         if tl_data.render_highlight.get() == 0 {
             return;
         }
@@ -333,6 +333,12 @@ impl Renderer<'_> {
         self.base.fill_scaled_boxes(slice::from_ref(bounds), &color);
     }
 
+    pub fn render_highlight(&mut self, rect: &Rect) {
+        let color = self.state.theme.colors.highlight.get();
+        self.base.ops.push(GfxApiOpt::Sync);
+        self.base.fill_boxes(slice::from_ref(rect), &color);
+    }
+
     pub fn render_surface(&mut self, surface: &WlSurface, x: i32, y: i32, bounds: Option<&Rect>) {
         let (x, y) = self.base.scale_point(x, y);
         self.render_surface_scaled(surface, x, y, None, bounds, false);

src/state.rs

@@ -586,7 +586,7 @@ impl State {
         }
         let seats = self.globals.seats.lock();
         for seat in seats.values() {
-            seat.trigger_tree_changed();
+            seat.trigger_tree_changed(false);
         }
     }
 

src/tree.rs

@@ -508,7 +508,6 @@ pub trait Node: 'static {
 
     // TYPE CONVERTERS
 
-    #[cfg_attr(not(feature = "it"), expect(dead_code))]
     fn node_into_float(self: Rc<Self>) -> Option<Rc<FloatNode>> {
         None
     }

src/tree/container.rs

@@ -17,8 +17,9 @@ use {
         state::State,
         text::TextTexture,
         tree::{
-            walker::NodeVisitor, ContainingNode, Direction, FindTreeResult, FindTreeUsecase,
+            default_tile_drag_bounds, walker::NodeVisitor, ContainingNode, Direction,
-            FoundNode, Node, NodeId, ToplevelData, ToplevelNode, ToplevelNodeBase, WorkspaceNode,
+            FindTreeResult, FindTreeUsecase, FoundNode, Node, NodeId, TddType, TileDragDestination,
+            ToplevelData, ToplevelNode, ToplevelNodeBase, WorkspaceNode,
         },
         utils::{
             asyncevent::AsyncEvent,
@@ -53,6 +54,15 @@ pub enum ContainerSplit {
     Vertical,
 }
 
+impl ContainerSplit {
+    pub fn other(self) -> Self {
+        match self {
+            ContainerSplit::Horizontal => ContainerSplit::Vertical,
+            ContainerSplit::Vertical => ContainerSplit::Horizontal,
+        }
+    }
+}
+
 impl From<Axis> for ContainerSplit {
     fn from(a: Axis) -> Self {
         match a {
@@ -547,6 +557,7 @@ impl ContainerNode {
 
     fn pointer_move(
         self: &Rc<Self>,
+        seat: &Rc<WlSeatGlobal>,
         id: CursorType,
         cursor: &CursorUser,
         x: Fixed,
@@ -574,7 +585,16 @@ impl ContainerNode {
         if let Some(op) = &seat_state.op {
             match op.kind {
                 SeatOpKind::Move => {
-                    // todo
+                    if let CursorType::Seat(_) = id {
+                        const DRAG_DIST: i32 = 10;
+                        let dx = x - op.x;
+                        let dy = y - op.y;
+                        if dx * dx + dy * dy > DRAG_DIST * DRAG_DIST {
+                            let node = op.child.node.clone();
+                            drop(seats);
+                            seat.start_tile_drag(&node);
+                        }
+                    }
                 }
                 SeatOpKind::Resize {
                     dist_left,
@@ -1233,20 +1253,220 @@ impl ContainerNode {
                 seat.set_tl_floating(child.node.clone(), true);
                 return;
             }
-            seat_data.op = Some(SeatOp { child, kind })
+            seat_data.op = Some(SeatOp {
+                child,
+                kind,
+                x: seat_data.x,
+                y: seat_data.y,
+            })
         } else if !pressed {
-            let op = seat_data.op.take().unwrap();
+            seat_data.op = None;
             drop(seat_datas);
-            if op.kind == SeatOpKind::Move {
+        }
-                // todo
+    }
+
+    fn tile_drag_destination_mono_titles(
+        self: &Rc<Self>,
+        source: NodeId,
+        abs_bounds: Rect,
+        abs_x: i32,
+        abs_y: i32,
+    ) -> Option<TileDragDestination> {
+        let mut prev_is_source = false;
+        let mut prev_center = 0;
+        for child in self.children.iter() {
+            if child.node.node_id() == source {
+                prev_is_source = true;
+                continue;
+            }
+            let rect = child.title_rect.get();
+            let center = (rect.x1() + rect.x2()) / 2;
+            if !prev_is_source {
+                let rect = Rect::new(prev_center, 0, center, rect.height())?
+                    .move_(self.abs_x1.get(), self.abs_y1.get())
+                    .intersect(abs_bounds);
+                if rect.contains(abs_x, abs_y) {
+                    return Some(TileDragDestination {
+                        highlight: rect,
+                        ty: TddType::Insert {
+                            container: self.clone(),
+                            neighbor: child.node.clone(),
+                            before: true,
+                        },
+                    });
+                }
+            }
+            prev_center = center;
+            prev_is_source = false;
+        }
+        if prev_is_source {
+            return None;
+        }
+        let last = self.children.last()?;
+        let rect = Rect::new(
+            prev_center,
+            0,
+            self.width.get(),
+            self.state.theme.sizes.title_height.get(),
+        )?
+        .move_(self.abs_x1.get(), self.abs_y1.get())
+        .intersect(abs_bounds);
+        if rect.contains(abs_x, abs_y) {
+            return Some(TileDragDestination {
+                highlight: rect,
+                ty: TddType::Insert {
+                    container: self.clone(),
+                    neighbor: last.node.clone(),
+                    before: false,
+                },
+            });
+        }
+        None
+    }
+
+    fn tile_drag_destination_mono(
+        self: &Rc<Self>,
+        mc: &ContainerChild,
+        source: NodeId,
+        abs_bounds: Rect,
+        abs_x: i32,
+        abs_y: i32,
+    ) -> Option<TileDragDestination> {
+        let th = self.state.theme.sizes.title_height.get();
+        if abs_y < self.abs_y1.get() + th {
+            return self.tile_drag_destination_mono_titles(source, abs_bounds, abs_x, abs_y);
+        }
+        let body = self.mono_body.get();
+        let bounds = body
+            .move_(self.abs_x1.get(), self.abs_y1.get())
+            .intersect(abs_bounds);
+        return mc
+            .node
+            .clone()
+            .tl_tile_drag_destination(source, None, bounds, abs_x, abs_y);
+    }
+
+    pub fn tile_drag_destination(
+        self: &Rc<Self>,
+        source: NodeId,
+        abs_bounds: Rect,
+        abs_x: i32,
+        abs_y: i32,
+    ) -> Option<TileDragDestination> {
+        if source == self.node_id() {
+            return None;
+        }
+        if let Some(mc) = self.mono_child.get() {
+            return self.tile_drag_destination_mono(&mc, source, abs_bounds, abs_x, abs_y);
+        }
+        let mut prev_is_source = false;
+        let mut prev_border_start = 0;
+        let split = self.split.get();
+        for child in self.children.iter() {
+            if child.node.node_id() == source {
+                prev_is_source = true;
+                continue;
+            }
+            let start_drag_bounds = child.node.tl_tile_drag_bounds(split, true);
+            let end_drag_bounds = child.node.tl_tile_drag_bounds(split, false);
+            let body = child.body.get();
+            let main_body_rect = {
+                match split {
+                    ContainerSplit::Horizontal => Rect::new(
+                        body.x1() + start_drag_bounds,
+                        body.y1(),
+                        body.x2() - end_drag_bounds,
+                        body.y2(),
+                    )?,
+                    ContainerSplit::Vertical => Rect::new(
+                        body.x1(),
+                        body.y1() + start_drag_bounds,
+                        body.x2(),
+                        body.y2() - end_drag_bounds,
+                    )?,
+                }
+                .move_(self.abs_x1.get(), self.abs_y1.get())
+                .intersect(abs_bounds)
+            };
+            if main_body_rect.contains(abs_x, abs_y) {
+                return child.node.clone().tl_tile_drag_destination(
+                    source,
+                    Some(split),
+                    main_body_rect,
+                    abs_x,
+                    abs_y,
+                );
+            }
+            if !prev_is_source {
+                let left_border_rect = {
+                    match split {
+                        ContainerSplit::Horizontal => Rect::new(
+                            prev_border_start,
+                            body.y1(),
+                            body.x1() + start_drag_bounds,
+                            body.y2(),
+                        )?,
+                        ContainerSplit::Vertical => Rect::new(
+                            body.x1(),
+                            prev_border_start,
+                            body.x2(),
+                            body.y1() + start_drag_bounds,
+                        )?,
+                    }
+                    .move_(self.abs_x1.get(), self.abs_y1.get())
+                    .intersect(abs_bounds)
+                };
+                if left_border_rect.contains(abs_x, abs_y) {
+                    return Some(TileDragDestination {
+                        highlight: left_border_rect,
+                        ty: TddType::Insert {
+                            container: self.clone(),
+                            neighbor: child.node.clone(),
+                            before: true,
+                        },
+                    });
+                }
+            }
+            prev_is_source = false;
+            prev_border_start = match split {
+                ContainerSplit::Horizontal => body.x2() - end_drag_bounds,
+                ContainerSplit::Vertical => body.y2() - end_drag_bounds,
+            };
+        }
+        if prev_is_source {
+            return None;
+        }
+        let last = self.children.last()?;
+        let body = last.body.get();
+        let right_border_rect = match split {
+            ContainerSplit::Horizontal => {
+                Rect::new(prev_border_start, body.y1(), body.x2(), body.y2())?
+            }
+            ContainerSplit::Vertical => {
+                Rect::new(body.x1(), prev_border_start, body.x2(), body.y2())?
             }
         }
+        .move_(self.abs_x1.get(), self.abs_y1.get())
+        .intersect(abs_bounds);
+        if right_border_rect.contains(abs_x, abs_y) {
+            return Some(TileDragDestination {
+                highlight: right_border_rect,
+                ty: TddType::Insert {
+                    container: self.clone(),
+                    neighbor: last.node.clone(),
+                    before: false,
+                },
+            });
+        }
+        None
     }
 }
 
 struct SeatOp {
     child: NodeRef<ContainerChild>,
     kind: SeatOpKind,
+    x: i32,
+    y: i32,
 }
 
 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
@@ -1452,6 +1672,7 @@ impl Node for ContainerNode {
     fn node_on_pointer_enter(self: Rc<Self>, seat: &Rc<WlSeatGlobal>, x: Fixed, y: Fixed) {
         // log::info!("node_on_pointer_enter");
         self.pointer_move(
+            seat,
             CursorType::Seat(seat.id()),
             seat.pointer_cursor(),
             x,
@@ -1460,6 +1681,14 @@ impl Node for ContainerNode {
         );
     }
 
+    fn node_on_leave(&self, seat: &WlSeatGlobal) {
+        let mut seats = self.cursors.borrow_mut();
+        let id = CursorType::Seat(seat.id());
+        if let Some(seat_state) = seats.get_mut(&id) {
+            seat_state.op = None;
+        }
+    }
+
     fn node_on_pointer_unfocus(&self, seat: &Rc<WlSeatGlobal>) {
         // log::info!("unfocus");
         let mut seats = self.cursors.borrow_mut();
@@ -1482,6 +1711,7 @@ impl Node for ContainerNode {
     fn node_on_pointer_motion(self: Rc<Self>, seat: &Rc<WlSeatGlobal>, x: Fixed, y: Fixed) {
         // log::info!("node_on_pointer_motion");
         self.pointer_move(
+            seat,
             CursorType::Seat(seat.id()),
             seat.pointer_cursor(),
             x,
@@ -1503,7 +1733,14 @@ impl Node for ContainerNode {
         y: Fixed,
     ) {
         tool.cursor().set_known(KnownCursor::Default);
-        self.pointer_move(CursorType::TabletTool(tool.id), tool.cursor(), x, y, true);
+        self.pointer_move(
+            tool.seat(),
+            CursorType::TabletTool(tool.id),
+            tool.cursor(),
+            x,
+            y,
+            true,
+        );
     }
 
     fn node_on_tablet_tool_apply_changes(
@@ -1515,7 +1752,7 @@ impl Node for ContainerNode {
         y: Fixed,
     ) {
         let id = CursorType::TabletTool(tool.id);
-        self.pointer_move(id, tool.cursor(), x, y, false);
+        self.pointer_move(tool.seat(), id, tool.cursor(), x, y, false);
         if let Some(changes) = changes {
             if let Some(pressed) = changes.down {
                 self.button(id, tool.seat(), time_usec, pressed, BTN_LEFT);
@@ -1914,6 +2151,31 @@ impl ToplevelNodeBase for ContainerNode {
     fn tl_admits_children(&self) -> bool {
         true
     }
+
+    fn tl_tile_drag_destination(
+        self: Rc<Self>,
+        source: NodeId,
+        _split: Option<ContainerSplit>,
+        abs_bounds: Rect,
+        abs_x: i32,
+        abs_y: i32,
+    ) -> Option<TileDragDestination> {
+        self.tile_drag_destination(source, abs_bounds, abs_x, abs_y)
+    }
+
+    fn tl_tile_drag_bounds(&self, split: ContainerSplit, start: bool) -> i32 {
+        if split != self.split.get() {
+            return default_tile_drag_bounds(self, split);
+        }
+        let child = match start {
+            true => self.children.first(),
+            false => self.children.last(),
+        };
+        let Some(child) = child else {
+            return 0;
+        };
+        child.node.tl_tile_drag_bounds(split, start) / 2
+    }
 }
 
 fn direction_to_split(dir: Direction) -> (ContainerSplit, bool) {
@@ -1925,3 +2187,118 @@ fn direction_to_split(dir: Direction) -> (ContainerSplit, bool) {
         Direction::Unspecified => (ContainerSplit::Horizontal, true),
     }
 }
+
+fn tile_drag_destination_in_mono(
+    tl: Rc<dyn ToplevelNode>,
+    abs_bounds: Rect,
+    abs_x: i32,
+    abs_y: i32,
+) -> TileDragDestination {
+    let mut x1 = abs_bounds.x1();
+    let mut x2 = abs_bounds.x2();
+    let mut y1 = abs_bounds.y1();
+    let mut y2 = abs_bounds.y2();
+    let dx = (x2 - x1) / 3;
+    let dy = (y2 - y1) / 3;
+    let mut split_before = true;
+    let mut split = ContainerSplit::Horizontal;
+    if abs_x < x1 + dx {
+        x2 = x1 + dx;
+    } else if abs_x > x2 - dx {
+        split_before = false;
+        x1 = x2 - dx;
+    } else {
+        split = ContainerSplit::Vertical;
+        x1 += dx;
+        x2 -= dx;
+        if abs_y < y1 + dy {
+            y2 = y1 + dy;
+        } else if abs_y > y2 - dy {
+            split_before = false;
+            y1 = y2 - dy;
+        } else {
+            let rect = Rect::new_unchecked(x1, y1 + dy, x2, y2 - dy);
+            return TileDragDestination {
+                highlight: rect,
+                ty: TddType::Replace(tl),
+            };
+        }
+    }
+    let rect = Rect::new_unchecked(x1, y1, x2, y2);
+    TileDragDestination {
+        highlight: rect,
+        ty: TddType::Split {
+            node: tl,
+            split,
+            before: split_before,
+        },
+    }
+}
+
+fn tile_drag_destination_in_split(
+    tl: Rc<dyn ToplevelNode>,
+    split: ContainerSplit,
+    abs_bounds: Rect,
+    mut abs_x: i32,
+    mut abs_y: i32,
+) -> TileDragDestination {
+    let mut x1 = abs_bounds.x1();
+    let mut x2 = abs_bounds.x2();
+    let mut y1 = abs_bounds.y1();
+    let mut y2 = abs_bounds.y2();
+    macro_rules! swap {
+        () => {
+            if split == ContainerSplit::Horizontal {
+                mem::swap(&mut x1, &mut y1);
+                mem::swap(&mut x2, &mut y2);
+                mem::swap(&mut abs_x, &mut abs_y);
+            }
+        };
+    }
+    swap!();
+    let mut split_before = false;
+    let mut split_after = false;
+    let dx = (x2 - x1) / 3;
+    if abs_x < x1 + dx {
+        split_before = true;
+        x2 = x1 + dx;
+    } else if abs_x < x2 - dx {
+        x1 += dx;
+        x2 -= dx;
+    } else {
+        split_after = true;
+        x1 = x2 - dx;
+    }
+    swap!();
+    let rect = Rect::new(x1, y1, x2, y2).unwrap();
+    let ty = if split_before || split_after {
+        TddType::Split {
+            node: tl,
+            split: split.other(),
+            before: split_before,
+        }
+    } else {
+        TddType::Replace(tl)
+    };
+    TileDragDestination {
+        highlight: rect,
+        ty,
+    }
+}
+
+pub fn default_tile_drag_destination(
+    tl: Rc<dyn ToplevelNode>,
+    source: NodeId,
+    split: Option<ContainerSplit>,
+    abs_bounds: Rect,
+    abs_x: i32,
+    abs_y: i32,
+) -> Option<TileDragDestination> {
+    if tl.node_id() == source {
+        return None;
+    }
+    Some(match split {
+        None => tile_drag_destination_in_mono(tl, abs_bounds, abs_x, abs_y),
+        Some(s) => tile_drag_destination_in_split(tl, s, abs_bounds, abs_x, abs_y),
+    })
+}

src/tree/display.rs

@@ -9,7 +9,7 @@ use {
         state::State,
         tree::{
             walker::NodeVisitor, FindTreeResult, FindTreeUsecase, FoundNode, Node, NodeId,
-            OutputNode, StackedNode,
+            OutputNode, StackedNode, TileDragDestination,
         },
         utils::{copyhashmap::CopyHashMap, linkedlist::LinkedList},
     },
@@ -83,6 +83,21 @@ impl DisplayNode {
             state.damage(self.extents.get());
         }
     }
+
+    pub fn tile_drag_destination(
+        &self,
+        source: NodeId,
+        x: i32,
+        y: i32,
+    ) -> Option<TileDragDestination> {
+        for output in self.outputs.lock().values() {
+            let pos = output.node_absolute_position();
+            if pos.contains(x, y) {
+                return output.tile_drag_destination(source, x, y);
+            }
+        }
+        None
+    }
 }
 
 impl Node for DisplayNode {

src/tree/float.rs

@@ -15,7 +15,7 @@ use {
         text::TextTexture,
         tree::{
             walker::NodeVisitor, ContainingNode, Direction, FindTreeResult, FindTreeUsecase,
-            FoundNode, Node, NodeId, StackedNode, ToplevelNode, WorkspaceNode,
+            FoundNode, Node, NodeId, StackedNode, TileDragDestination, ToplevelNode, WorkspaceNode,
         },
         utils::{
             asyncevent::AsyncEvent, clonecell::CloneCell, double_click_state::DoubleClickState,
@@ -528,6 +528,26 @@ impl FloatNode {
             self.set_workspace(&ws);
         }
     }
+
+    pub fn tile_drag_destination(
+        self: &Rc<Self>,
+        source: NodeId,
+        abs_x: i32,
+        abs_y: i32,
+    ) -> Option<TileDragDestination> {
+        let child = self.child.get()?;
+        let theme = &self.state.theme.sizes;
+        let bw = theme.border_width.get();
+        let th = theme.title_height.get();
+        let pos = self.position.get();
+        let body = Rect::new(
+            pos.x1() + bw,
+            pos.y1() + bw + th + 1,
+            pos.x2() - bw,
+            pos.y2() - bw,
+        )?;
+        child.tl_tile_drag_destination(source, None, body, abs_x, abs_y)
+    }
 }
 
 impl Debug for FloatNode {

src/tree/output.rs

@@ -33,7 +33,7 @@ use {
         text::TextTexture,
         tree::{
             walker::NodeVisitor, Direction, FindTreeResult, FindTreeUsecase, FoundNode, Node,
-            NodeId, StackedNode, WorkspaceNode,
+            NodeId, StackedNode, TddType, TileDragDestination, WorkspaceNode,
         },
         utils::{
             asyncevent::AsyncEvent, clonecell::CloneCell, copyhashmap::CopyHashMap,
@@ -522,6 +522,10 @@ impl OutputNode {
                 return ws;
             }
         }
+        self.generate_workspace()
+    }
+
+    pub fn generate_workspace(self: &Rc<Self>) -> Rc<WorkspaceNode> {
         let name = 'name: {
             for i in 1.. {
                 let name = i.to_string();
@@ -937,6 +941,85 @@ impl OutputNode {
         };
         self.global.connector.connector.set_tearing_enabled(enabled);
     }
+
+    pub fn tile_drag_destination(
+        self: &Rc<Self>,
+        source: NodeId,
+        x_abs: i32,
+        y_abs: i32,
+    ) -> Option<TileDragDestination> {
+        if self.state.lock.locked.get() {
+            return None;
+        }
+        for stacked in self.state.root.stacked.rev_iter() {
+            let Some(float) = stacked.deref().clone().node_into_float() else {
+                continue;
+            };
+            if !float.node_visible() {
+                continue;
+            }
+            let pos = float.node_absolute_position();
+            if !pos.contains(x_abs, y_abs) {
+                continue;
+            }
+            return float.tile_drag_destination(source, x_abs, y_abs);
+        }
+        let rect = self.non_exclusive_rect.get();
+        if !rect.contains(x_abs, y_abs) {
+            return None;
+        }
+        let Some(ws) = self.workspace.get() else {
+            return Some(TileDragDestination {
+                highlight: rect,
+                ty: TddType::NewWorkspace {
+                    output: self.clone(),
+                },
+            });
+        };
+        if ws.fullscreen.is_some() {
+            return None;
+        }
+        let th = self.state.theme.sizes.title_height.get();
+        if y_abs < rect.y1() + th + 1 {
+            let rd = &*self.render_data.borrow();
+            let (x, _) = rect.translate(x_abs, y_abs);
+            let mut last_x2 = 0;
+            for t in &rd.titles {
+                if x < t.x2 {
+                    return Some(TileDragDestination {
+                        highlight: Rect::new_sized(rect.x1() + t.x1, rect.y1(), t.x2 - t.x1, th)?,
+                        ty: TddType::MoveToWorkspace {
+                            workspace: t.ws.clone(),
+                        },
+                    });
+                }
+                last_x2 = t.x2;
+            }
+            return Some(TileDragDestination {
+                highlight: Rect::new_sized(
+                    rect.x1() + last_x2,
+                    rect.y1(),
+                    rect.x2() - last_x2,
+                    th,
+                )?,
+                ty: TddType::MoveToNewWorkspace {
+                    output: self.clone(),
+                },
+            });
+        }
+        let thp1 = self.state.theme.sizes.title_height.get() + 1;
+        let rect = Rect::new(rect.x1(), rect.y1() + thp1, rect.x2(), rect.y2())?;
+        if !rect.contains(x_abs, y_abs) {
+            return None;
+        }
+        let Some(c) = ws.container.get() else {
+            return Some(TileDragDestination {
+                highlight: rect,
+                ty: TddType::NewContainer { workspace: ws },
+            });
+        };
+        c.tile_drag_destination(source, rect, x_abs, y_abs)
+    }
 }
 
 pub struct OutputTitle {

src/tree/placeholder.rs

@@ -10,7 +10,8 @@ use {
         state::State,
         text::TextTexture,
         tree::{
-            Direction, FindTreeResult, FindTreeUsecase, FoundNode, Node, NodeId, NodeVisitor,
+            default_tile_drag_destination, ContainerSplit, Direction, FindTreeResult,
+            FindTreeUsecase, FoundNode, Node, NodeId, NodeVisitor, TileDragDestination,
             ToplevelData, ToplevelNode, ToplevelNodeBase,
         },
         utils::{
@@ -62,6 +63,17 @@ impl PlaceholderNode {
         }
     }
 
+    pub fn new_empty(state: &Rc<State>) -> Self {
+        Self {
+            id: state.node_ids.next(),
+            toplevel: ToplevelData::new(state, String::new(), None),
+            destroyed: Default::default(),
+            update_textures_scheduled: Default::default(),
+            state: state.clone(),
+            textures: Default::default(),
+        }
+    }
+
     pub fn is_destroyed(&self) -> bool {
         self.destroyed.get()
     }
@@ -222,4 +234,15 @@ impl ToplevelNodeBase for PlaceholderNode {
     fn tl_admits_children(&self) -> bool {
         false
     }
+
+    fn tl_tile_drag_destination(
+        self: Rc<Self>,
+        source: NodeId,
+        split: Option<ContainerSplit>,
+        abs_bounds: Rect,
+        x: i32,
+        y: i32,
+    ) -> Option<TileDragDestination> {
+        default_tile_drag_destination(self, source, split, abs_bounds, x, y)
+    }
 }

src/tree/toplevel.rs

@@ -11,7 +11,10 @@ use {
         },
         rect::Rect,
         state::State,
-        tree::{ContainingNode, Direction, Node, OutputNode, PlaceholderNode, WorkspaceNode},
+        tree::{
+            ContainerNode, ContainerSplit, ContainingNode, Direction, Node, NodeId, OutputNode,
+            PlaceholderNode, WorkspaceNode,
+        },
         utils::{
             clonecell::CloneCell,
             copyhashmap::CopyHashMap,
@@ -202,6 +205,20 @@ pub trait ToplevelNodeBase: Node {
     }
 
     fn tl_admits_children(&self) -> bool;
+
+    fn tl_tile_drag_destination(
+        self: Rc<Self>,
+        source: NodeId,
+        split: Option<ContainerSplit>,
+        abs_bounds: Rect,
+        abs_x: i32,
+        abs_y: i32,
+    ) -> Option<TileDragDestination>;
+
+    fn tl_tile_drag_bounds(&self, split: ContainerSplit, start: bool) -> i32 {
+        let _ = start;
+        default_tile_drag_bounds(self, split)
+    }
 }
 
 pub struct FullscreenedData {
@@ -532,3 +549,42 @@ impl ToplevelData {
         }
     }
 }
+
+pub struct TileDragDestination {
+    pub highlight: Rect,
+    pub ty: TddType,
+}
+
+pub enum TddType {
+    Replace(Rc<dyn ToplevelNode>),
+    Split {
+        node: Rc<dyn ToplevelNode>,
+        split: ContainerSplit,
+        before: bool,
+    },
+    Insert {
+        container: Rc<ContainerNode>,
+        neighbor: Rc<dyn ToplevelNode>,
+        before: bool,
+    },
+    NewWorkspace {
+        output: Rc<OutputNode>,
+    },
+    NewContainer {
+        workspace: Rc<WorkspaceNode>,
+    },
+    MoveToWorkspace {
+        workspace: Rc<WorkspaceNode>,
+    },
+    MoveToNewWorkspace {
+        output: Rc<OutputNode>,
+    },
+}
+
+pub fn default_tile_drag_bounds<T: ToplevelNodeBase + ?Sized>(t: &T, split: ContainerSplit) -> i32 {
+    const FACTOR: i32 = 5;
+    match split {
+        ContainerSplit::Horizontal => t.node_absolute_position().width() / FACTOR,
+        ContainerSplit::Vertical => t.node_absolute_position().height() / FACTOR,
+    }
+}