Fix canvas rect

src/view.rs

@@ -580,19 +580,19 @@ impl CanvasView {
         // *canvas*, and egui clips interaction rectangles to it, so the clip
         // has to be corrected before anything in the layer is interacted with:
         // otherwise the background stops responding as soon as the view is
-        // panned away from where it started.
+        // panned away from where it started. The correction is the visible
+        // area and not a pixel more: the layer paints above the panels, so a
+        // background reaching past the central panel would sit on top of the
+        // inspector and swallow the clicks meant for its widgets.
         let visible = self.to_global.inverse() * outer;
-        let background_rect = visible.expand(visible.width().max(visible.height()));
+        scene.set_clip_rect(visible);
-        scene.set_clip_rect(background_rect);
         let background = scene.interact(
-            background_rect,
+            visible,
             scene.id().with("background"),
             Sense::click_and_drag(),
         );
         self.handle_pan_and_zoom(&scene, &background);
 
-        let visible = self.to_global.inverse() * outer;
-        scene.set_clip_rect(visible);
         ui.ctx().set_transform_layer(layer, self.to_global);
 
         if self.show_grid {
@@ -1694,6 +1694,40 @@ mod tests {
         .drop_without_applying_deltas();
     }
 
+    /// Like `pass`, but with a panel on the right the way the app puts the
+    /// inspector there. Reports whether the widget filling that panel was
+    /// clicked.
+    fn pass_beside_a_panel(
+        ctx: &egui::Context,
+        view: &mut CanvasView,
+        doc: &mut Document,
+        screen: Rect,
+        events: Vec<egui::Event>,
+    ) -> bool {
+        let palette = Palette::dark();
+        let input = egui::RawInput {
+            screen_rect: Some(screen),
+            events,
+            ..Default::default()
+        };
+        let mut clicked = false;
+        ctx.run_ui(input, |ui| {
+            egui::Panel::right("inspector")
+                .default_size(300.0)
+                .show(ui, |ui| {
+                    let size = ui.available_size();
+                    clicked = ui.add_sized(size, egui::Button::new("A control")).clicked();
+                });
+            egui::CentralPanel::default()
+                .frame(egui::Frame::NONE)
+                .show(ui, |ui| {
+                    view.show(ui, doc, &palette);
+                });
+        })
+        .drop_without_applying_deltas();
+        clicked
+    }
+
     fn click(at: Pos2) -> egui::Event {
         egui::Event::PointerButton {
             pos: at,
@@ -1771,6 +1805,32 @@ mod tests {
         );
     }
 
+    #[test]
+    fn a_click_in_the_inspector_stays_in_the_inspector() {
+        let ctx = egui::Context::default();
+        let mut doc = Document::new();
+        doc.canvas = canvas_with_two_nodes();
+        let mut view = CanvasView::new();
+        view.selection.set_node("a");
+
+        let screen = Rect::from_min_size(Pos2::ZERO, vec2(1200.0, 900.0));
+        let at = pos2(1050.0, 450.0);
+        let mut hit = false;
+        for events in [
+            vec![egui::Event::PointerMoved(at)],
+            vec![click(at)],
+            vec![release(at)],
+        ] {
+            hit |= pass_beside_a_panel(&ctx, &mut view, &mut doc, screen, events);
+        }
+
+        assert!(hit, "the widget in the panel never saw the click");
+        assert!(
+            view.selection.has_node("a"),
+            "the canvas took a click that belonged to the panel"
+        );
+    }
+
     fn canvas_with_two_nodes() -> Canvas {
         let mut canvas = Canvas::default();
         canvas.nodes.push(Node::new(