feat(ui): a dragged dialog may go partly off-screen

ROADMAP.md

@@ -129,7 +129,7 @@ list) · [roadmap.md](docs/roadmap.md) (milestones, plan) · [parity-checklist.m
 
 Newest first.
 
-- **2026-10-13** · Dialogs and the About window move when you drag their title row, so the page behind them can be seen. A dragged dialog stays inside the window, and each dialog opens centred. No readiness percentage change.
+- **2026-10-13** · Dialogs and the About window move when you drag their title row, so the page behind them can be seen. A dragged dialog may go partly off-screen, but its title row stays reachable; each dialog opens centred, and again after the window is resized. No readiness percentage change.
 - **2026-10-12** · macOS Dock Quit uses the same unsaved-document prompts as window and menu Quit. Repeated requests keep the current answers; Cancel retains every tab and unsaved recovery checkpoint, and completed Save/Don't Save answers exit through the ordinary event loop. No readiness percentage change.
 - **2026-10-12** · Orderly native exit writes the latest recovery state after finalizing current quit approvals; incomplete or stale plans keep their documents, and Undo to the saved state clears stale recovery. Unavailable or failed recovery is reported. Cancelable macOS Dock Quit remains open (#544). No readiness percentage change.
 - **2026-10-12** · Recovered documents keep a checkpoint until saved, closed or reverted, including a second crash before autosave. Restarted document IDs and explicit recovery folders preserve other snapshots; failed republishing retains the original. No readiness percentage change.

crates/ui-egui/src/dialogs.rs

@@ -4833,10 +4833,10 @@ mod tests {
         drag(&mut h, body, body + vec2(-150.0, 80.0));
         assert_eq!(rect(&h), moved, "a drag in the body leaves the dialog in place");
 
-        // The dialog stays inside the window.
+        // The title row stays inside the top edge.
         let title = h.get_by_label("Create Table").rect().center();
         drag(&mut h, title, title - vec2(0.0, 1000.0));
-        assert!(rect(&h).top() >= 0.0, "{:?}", rect(&h));
+        assert!(rect(&h).top().abs() < 1.0, "{:?}", rect(&h));
 
         // Opened again, the dialog starts centred.
         h.state_mut().ui.dialog = None;
@@ -4844,5 +4844,10 @@ mod tests {
         h.state_mut().ui.dialog = Some(Dialog::new("insertTable", Value::Null));
         h.run_steps(4);
         assert!((rect(&h).center() - centred.center()).length() < 1.0, "{:?}", rect(&h));
+
+        // Past the left edge, about 100 px of the title row stays inside.
+        let title = h.get_by_label("Create Table").rect().center();
+        drag(&mut h, title, title - vec2(900.0, 0.0));
+        assert!((rect(&h).right() - 100.0).abs() < 2.0, "{:?}", rect(&h));
     }
 }

crates/ui-egui/src/modal_drag.rs

@@ -1,16 +1,24 @@
 //! Modal windows (dialogs, About) that the user moves by dragging their title row.
 //!
 //! The modal stays anchored at the centre of the window and is shifted by an offset kept in
-//! egui's temporary memory. A modal that was not shown in the previous pass starts centred.
-//! egui keeps the whole modal inside the window, so its title row stays reachable.
+//! egui's temporary memory. A modal that was not shown in the previous pass, or whose window
+//! changed size, starts centred. An undragged modal keeps egui's constraint to the window; a
+//! dragged one may go partly off-screen, but its title row stays reachable.
 
 use egui::{Align2, Context, CursorIcon, Id, Modal, Rect, Sense, Ui, Vec2, vec2};
 
+/// How much of the title row's width stays inside the window.
+const KEEP_VISIBLE: f32 = 100.0;
+
 #[derive(Clone, Copy, Default)]
 struct Placement {
     offset: Vec2,
     /// The pass the modal was last shown in: a gap means it was closed and opened again.
     pass: u64,
+    /// The window content size the offset belongs to.
+    content: Vec2,
+    /// From the top of the modal to the bottom of its title row.
+    title_height: f32,
 }
 
 /// A modal centred in the window and shifted by the user's drag.
@@ -23,16 +31,20 @@ pub(crate) fn modal(ctx: &Context, area: Id, instance: Id) -> Modal {
     let content = ctx.content_rect();
     let offset = ctx.data_mut(|d| {
         let p = d.get_temp_mut_or_default::<Placement>(instance);
-        if p.pass.saturating_add(1) < pass {
-            *p = Placement::default();
+        if p.pass.saturating_add(1) < pass || p.content != content.size() {
+            *p = Placement { content: content.size(), ..Placement::default() };
         }
         p.pass = pass;
-        if let Some(size) = size {
-            p.offset = clamp(p.offset, size, content);
+        if let Some(size) = size
+            && p.offset != Vec2::ZERO
+        {
+            p.offset = clamp(p.offset, size, p.title_height, content);
         }
         p.offset
     });
-    Modal::new(area).area(Modal::default_area(area).anchor(Align2::CENTER_CENTER, offset))
+    // Dragged: `clamp` keeps the title row reachable instead of egui keeping the whole modal inside.
+    let constrained = offset == Vec2::ZERO;
+    Modal::new(area).area(Modal::default_area(area).anchor(Align2::CENTER_CENTER, offset).constrain(constrained))
 }
 
 /// Makes `rect`, the modal's title row, drag the modal opened with [`modal`] for `instance`.
@@ -40,18 +52,29 @@ pub(crate) fn modal(ctx: &Context, area: Id, instance: Id) -> Modal {
 /// Widgets registered after this call sit on top of the drag area and keep their own input.
 pub(crate) fn title_drag(ui: &Ui, instance: Id, rect: Rect) {
     let resp = ui.interact(rect, instance.with("title_drag"), Sense::drag());
+    let delta = if resp.dragged() { resp.drag_delta() } else { Vec2::ZERO };
+    let top = ui.ctx().memory(|m| m.area_rect(ui.layer_id().id)).map_or(rect.top(), |r| r.top());
+    ui.ctx().data_mut(|d| {
+        let p = d.get_temp_mut_or_default::<Placement>(instance);
+        p.offset += delta;
+        p.title_height = (rect.bottom() - top).max(0.0);
+    });
     if resp.dragged() {
-        let delta = resp.drag_delta();
-        ui.ctx().data_mut(|d| d.get_temp_mut_or_default::<Placement>(instance).offset += delta);
         ui.ctx().set_cursor_icon(CursorIcon::Grabbing);
     } else if resp.hovered() {
         ui.ctx().set_cursor_icon(CursorIcon::Grab);
     }
 }
 
-/// Limits `offset` to the range in which a modal of `size` fits inside `content`, the range egui
-/// constrains it to, so dragging back from beyond an edge moves it at once.
-fn clamp(offset: Vec2, size: Vec2, content: Rect) -> Vec2 {
-    let room = ((content.size() - size) * 0.5).max(Vec2::ZERO);
-    vec2(offset.x.min(room.x).max(-room.x), offset.y.min(room.y).max(-room.y))
+/// Limits `offset` so the title row of a modal of `size` stays inside `content` vertically and
+/// [`KEEP_VISIBLE`] of its width stays inside horizontally. A modal taller than the window keeps
+/// its top edge inside.
+fn clamp(offset: Vec2, size: Vec2, title_height: f32, content: Rect) -> Vec2 {
+    let centred = Align2::CENTER_CENTER.align_size_within_rect(size, content);
+    let keep = KEEP_VISIBLE.min(size.x);
+    let x_lo = content.left() + keep - size.x - centred.left();
+    let x_hi = content.right() - keep - centred.left();
+    let y_lo = content.top() - centred.top();
+    let y_hi = content.bottom() - title_height.min(size.y) - centred.top();
+    vec2(offset.x.min(x_hi).max(x_lo), offset.y.min(y_hi).max(y_lo))
 }