diff --git a/crates/ui-egui/src/canvas.rs b/crates/ui-egui/src/canvas.rs
index 1d14b60c..818a9f5f 100644
--- a/crates/ui-egui/src/canvas.rs
+++ b/crates/ui-egui/src/canvas.rs
@@ -142,6 +142,15 @@ pub fn show(app: &mut SlideApp, ui: &mut Ui) {
     let avail = ui.available_rect_before_wrap();
     app.canvas_rect = Some(avail);
     let Some(st) = app.session.active() else { return };
+    // The leftover fraction of a wheel line belongs to one presentation. Drop it whenever another
+    // one is drawn here, hovered or not, so switching away and back starts from zero.
+    let carry_id = ui.id().with("wheel_carry");
+    let doc_uid = st.uid;
+    ui.data_mut(|d| {
+        if d.get_temp::<(u64, f32)>(carry_id).is_none_or(|(uid, _)| uid != doc_uid) {
+            d.insert_temp(carry_id, (doc_uid, 0.0_f32));
+        }
+    });
     if st.doc.slides.is_empty() && st.selection.target == Target::Slides {
         let resp = ui.allocate_rect(avail, Sense::click());
         ui.painter().text(avail.center(), Align2::CENTER_CENTER, "Click to add first slide", theme::font(22.0), t.text_dim);
@@ -177,13 +186,7 @@ pub fn show(app: &mut SlideApp, ui: &mut Ui) {
         if overflow != egui::Vec2::ZERO {
             offset -= wheel;
         } else if !app.anim_preview_active() && app.session.tool.marquee.is_none() && !app.session.tool.dragging() {
-            // The leftover fraction belongs to one presentation: another one starts from zero.
-            let carry_id = ui.id().with("wheel_carry");
-            let (carry_doc, mut carry): (Option<u64>, f32) = ui.data_mut(|d| d.get_temp(carry_id).unwrap_or_default());
-            let doc_uid = app.session.active().map(|d| d.uid);
-            if carry_doc != doc_uid {
-                carry = 0.0;
-            }
+            let (_, mut carry): (u64, f32) = ui.data_mut(|d| d.get_temp(carry_id).unwrap_or_default());
             let wheel_step = app.session.active().and_then(|d| {
                 let current = d.selection.slide;
                 ui.input(|i| wheel_slide_target(&i.events, current, d.doc.slides.len(), &mut carry)).map(|target| (current, target))
diff --git a/crates/ui-egui/src/lib.rs b/crates/ui-egui/src/lib.rs
index b7759cc8..c898465c 100644
--- a/crates/ui-egui/src/lib.rs
+++ b/crates/ui-egui/src/lib.rs
@@ -3393,6 +3393,7 @@ mod tests {
         mouse_wheel(&mut h, &[-0.75]);
         assert_eq!(slide_at(h.state()), 0);
 
+        let a = h.state().session.active_index().unwrap();
         h.state_mut().run("file.new", json!({})).unwrap();
         h.state_mut().run("slide.new", json!({})).unwrap();
         h.state_mut().run("slide.go", json!({"index": 0})).unwrap();
@@ -3402,6 +3403,23 @@ mod tests {
         assert_eq!(slide_at(h.state()), 0, "a quarter line in the new presentation does not turn the page");
         mouse_wheel(&mut h, &[-0.75]);
         assert_eq!(slide_at(h.state()), 1, "a whole line in the new presentation does");
+
+        // Back in the first one, leave 0.75 of a line, then switch away and back with the pointer
+        // off the canvas (on the tabs): the canvas never sees a hover in the other presentation.
+        let b = h.state().session.active_index().unwrap();
+        h.state_mut().session.set_active(a);
+        h.state_mut().ui.zoom = Some(0.4);
+        h.run_steps(2);
+        mouse_wheel(&mut h, &[-0.75]);
+        assert_eq!(slide_at(h.state()), 0);
+        h.input_mut().events.push(egui::Event::PointerMoved(egui::pos2(-10.0, -10.0)));
+        h.run_steps(1);
+        h.state_mut().session.set_active(b);
+        h.run_steps(2);
+        h.state_mut().session.set_active(a);
+        h.run_steps(2);
+        mouse_wheel(&mut h, &[-0.25]);
+        assert_eq!(slide_at(h.state()), 0, "switching away without a hover still drops the fraction");
     }
 
     #[test]