From ca7ebb6c730151e75d1f354b7cadaa72e8d7c441 Mon Sep 17 00:00:00 2001
From: Lucas Meurer <lucasmeurer96@gmail.com>
Date: Mon, 1 Apr 2024 22:36:21 +0200
Subject: [PATCH 1/7] Fix scroll_with_delta only scrolling if the ScrollArea is
 focussed

---
 crates/egui/src/containers/scroll_area.rs  |  4 +++-
 crates/egui/src/input_state.rs             | 10 ++++++++++
 crates/egui/src/ui.rs                      |  6 ++++--
 crates/egui_demo_lib/src/demo/scrolling.rs |  8 ++++++++
 4 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/crates/egui/src/containers/scroll_area.rs b/crates/egui/src/containers/scroll_area.rs
index c448269fb0c..f06d57d1c73 100644
--- a/crates/egui/src/containers/scroll_area.rs
+++ b/crates/egui/src/containers/scroll_area.rs
@@ -870,7 +870,8 @@ impl Prepared {
 
         let max_offset = content_size - inner_rect.size();
         let is_hovering_outer_rect = ui.rect_contains_pointer(outer_rect);
-        if scrolling_enabled && is_hovering_outer_rect {
+        let force_current_scroll_area = ui.input(|i| i.force_current_scroll_area);
+        if scrolling_enabled && is_hovering_outer_rect || force_current_scroll_area {
             let always_scroll_enabled_direction = ui.style().always_scroll_the_only_direction
                 && scroll_enabled[0] != scroll_enabled[1];
             for d in 0..2 {
@@ -898,6 +899,7 @@ impl Prepared {
                             } else {
                                 input.smooth_scroll_delta[d] = 0.0;
                             }
+                            input.force_current_scroll_area = false;
                         });
 
                         state.scroll_stuck_to_end[d] = false;
diff --git a/crates/egui/src/input_state.rs b/crates/egui/src/input_state.rs
index 9c6103e0a54..ff6a1165e31 100644
--- a/crates/egui/src/input_state.rs
+++ b/crates/egui/src/input_state.rs
@@ -70,6 +70,10 @@ pub struct InputState {
     /// at the end of the frame this will be zero if a scroll-area consumed the delta.
     pub smooth_scroll_delta: Vec2,
 
+    /// Force the current scroll area to consume the [Self::smooth_scroll_delta], independent of the focus / mouse position.
+    /// This is used when using [crate::Ui::scroll_with_delta] to scroll the current scroll area.
+    pub(crate) force_current_scroll_area: bool,
+
     /// Zoom scale factor this frame (e.g. from ctrl-scroll or pinch gesture).
     ///
     /// * `zoom = 1`: no change.
@@ -154,6 +158,7 @@ impl Default for InputState {
             unprocessed_scroll_delta: Vec2::ZERO,
             raw_scroll_delta: Vec2::ZERO,
             smooth_scroll_delta: Vec2::ZERO,
+            force_current_scroll_area: false,
             zoom_factor_delta: 1.0,
             screen_rect: Rect::from_min_size(Default::default(), vec2(10_000.0, 10_000.0)),
             pixels_per_point: 1.0,
@@ -255,6 +260,7 @@ impl InputState {
             unprocessed_scroll_delta,
             raw_scroll_delta,
             smooth_scroll_delta,
+            force_current_scroll_area: false,
             zoom_factor_delta,
             screen_rect,
             pixels_per_point,
@@ -1113,6 +1119,7 @@ impl InputState {
             unprocessed_scroll_delta,
             raw_scroll_delta,
             smooth_scroll_delta,
+            force_current_scroll_area,
 
             zoom_factor_delta,
             screen_rect,
@@ -1157,6 +1164,9 @@ impl InputState {
         ui.label(format!(
             "smooth_scroll_delta: {smooth_scroll_delta:?} points"
         ));
+        ui.label(format!(
+            "force_current_scroll_area: {force_current_scroll_area}"
+        ));
         ui.label(format!("zoom_factor_delta: {zoom_factor_delta:4.2}x"));
         ui.label(format!("screen_rect: {screen_rect:?} points"));
         ui.label(format!(
diff --git a/crates/egui/src/ui.rs b/crates/egui/src/ui.rs
index 9ff05a267e8..ac14cfe3aa1 100644
--- a/crates/egui/src/ui.rs
+++ b/crates/egui/src/ui.rs
@@ -1091,8 +1091,10 @@ impl Ui {
     /// # });
     /// ```
     pub fn scroll_with_delta(&self, delta: Vec2) {
-        self.ctx()
-            .input_mut(|input| input.smooth_scroll_delta += delta);
+        self.ctx().input_mut(|input| {
+            input.smooth_scroll_delta += delta;
+            input.force_current_scroll_area = true;
+        });
     }
 }
 
diff --git a/crates/egui_demo_lib/src/demo/scrolling.rs b/crates/egui_demo_lib/src/demo/scrolling.rs
index 9c490d23d8a..d7bee754c5b 100644
--- a/crates/egui_demo_lib/src/demo/scrolling.rs
+++ b/crates/egui_demo_lib/src/demo/scrolling.rs
@@ -258,6 +258,7 @@ impl super::View for ScrollTo {
         let mut go_to_scroll_offset = false;
         let mut scroll_top = false;
         let mut scroll_bottom = false;
+        let mut scroll_delta = None;
 
         ui.horizontal(|ui| {
             ui.label("Scroll to a specific item index:");
@@ -292,6 +293,9 @@ impl super::View for ScrollTo {
         ui.horizontal(|ui| {
             scroll_top |= ui.button("Scroll to top").clicked();
             scroll_bottom |= ui.button("Scroll to bottom").clicked();
+            if ui.button("Scroll down by 64px").clicked() {
+                scroll_delta = Some(Vec2::new(0.0, -64.0));
+            }
         });
 
         let mut scroll_area = ScrollArea::vertical().max_height(200.0).auto_shrink(false);
@@ -305,6 +309,10 @@ impl super::View for ScrollTo {
                 if scroll_top {
                     ui.scroll_to_cursor(Some(Align::TOP));
                 }
+                if let Some(scroll_delta) = scroll_delta {
+                    ui.scroll_with_delta(scroll_delta);
+                }
+
                 ui.vertical(|ui| {
                     for item in 1..=num_items {
                         if track_item && item == self.track_item {

From 5c4c1910845fc1a7622dda0a99bf13b7d1fc3487 Mon Sep 17 00:00:00 2001
From: Lucas Meurer <lucasmeurer96@gmail.com>
Date: Tue, 2 Apr 2024 13:11:38 +0200
Subject: [PATCH 2/7] Add scroll_delta to FrameState

---
 crates/egui/src/containers/scroll_area.rs  | 63 +++++++++++-----------
 crates/egui/src/frame_state.rs             |  8 ++-
 crates/egui/src/input_state.rs             | 10 ----
 crates/egui/src/ui.rs                      |  5 +-
 crates/egui_demo_lib/src/demo/scrolling.rs |  2 +-
 5 files changed, 43 insertions(+), 45 deletions(-)

diff --git a/crates/egui/src/containers/scroll_area.rs b/crates/egui/src/containers/scroll_area.rs
index f06d57d1c73..b3a4e6b9f64 100644
--- a/crates/egui/src/containers/scroll_area.rs
+++ b/crates/egui/src/containers/scroll_area.rs
@@ -785,12 +785,12 @@ impl Prepared {
         for d in 0..2 {
             // We always take both scroll targets regardless of which scroll axes are enabled. This
             // is to avoid them leaking to other scroll areas.
-            let scroll_target = content_ui
-                .ctx()
-                .frame_state_mut(|state| state.scroll_target[d].take());
+            let (scroll_target, scroll_delta) = content_ui.ctx().frame_state_mut(|state| {
+                (state.scroll_target[d].take(), state.scroll_delta[d].take())
+            });
 
             if scroll_enabled[d] {
-                if let Some((target_range, align)) = scroll_target {
+                let mut delta = if let Some((target_range, align)) = scroll_target {
                     let min = content_ui.min_rect().min[d];
                     let clip_rect = content_ui.clip_rect();
                     let visible_range = min..=min + clip_rect.size()[d];
@@ -799,7 +799,7 @@ impl Prepared {
                     let clip_end = clip_rect.max[d];
                     let mut spacing = ui.spacing().item_spacing[d];
 
-                    let delta = if let Some(align) = align {
+                    if let Some(align) = align {
                         let center_factor = align.to_factor();
 
                         let offset =
@@ -816,31 +816,36 @@ impl Prepared {
                     } else {
                         // Ui is already in view, no need to adjust scroll.
                         0.0
-                    };
+                    }
+                } else {
+                    0.0
+                };
 
-                    if delta != 0.0 {
-                        let target_offset = state.offset[d] + delta;
+                if let Some(scroll_delta) = scroll_delta {
+                    delta += scroll_delta;
+                }
 
-                        if !animated {
-                            state.offset[d] = target_offset;
-                        } else if let Some(animation) = &mut state.offset_target[d] {
-                            // For instance: the user is continuously calling `ui.scroll_to_cursor`,
-                            // so we don't want to reset the animation, but perhaps update the target:
-                            animation.target_offset = target_offset;
-                        } else {
-                            // The further we scroll, the more time we take.
-                            // TODO(emilk): let users configure this in `Style`.
-                            let now = ui.input(|i| i.time);
-                            let points_per_second = 1000.0;
-                            let animation_duration =
-                                (delta.abs() / points_per_second).clamp(0.1, 0.3);
-                            state.offset_target[d] = Some(ScrollTarget {
-                                animation_time_span: (now, now + animation_duration as f64),
-                                target_offset,
-                            });
-                        }
-                        ui.ctx().request_repaint();
+                if delta != 0.0 {
+                    let target_offset = state.offset[d] + delta;
+
+                    if !animated {
+                        state.offset[d] = target_offset;
+                    } else if let Some(animation) = &mut state.offset_target[d] {
+                        // For instance: the user is continuously calling `ui.scroll_to_cursor`,
+                        // so we don't want to reset the animation, but perhaps update the target:
+                        animation.target_offset = target_offset;
+                    } else {
+                        // The further we scroll, the more time we take.
+                        // TODO(emilk): let users configure this in `Style`.
+                        let now = ui.input(|i| i.time);
+                        let points_per_second = 1000.0;
+                        let animation_duration = (delta.abs() / points_per_second).clamp(0.1, 0.3);
+                        state.offset_target[d] = Some(ScrollTarget {
+                            animation_time_span: (now, now + animation_duration as f64),
+                            target_offset,
+                        });
                     }
+                    ui.ctx().request_repaint();
                 }
             }
         }
@@ -870,8 +875,7 @@ impl Prepared {
 
         let max_offset = content_size - inner_rect.size();
         let is_hovering_outer_rect = ui.rect_contains_pointer(outer_rect);
-        let force_current_scroll_area = ui.input(|i| i.force_current_scroll_area);
-        if scrolling_enabled && is_hovering_outer_rect || force_current_scroll_area {
+        if scrolling_enabled && is_hovering_outer_rect {
             let always_scroll_enabled_direction = ui.style().always_scroll_the_only_direction
                 && scroll_enabled[0] != scroll_enabled[1];
             for d in 0..2 {
@@ -899,7 +903,6 @@ impl Prepared {
                             } else {
                                 input.smooth_scroll_delta[d] = 0.0;
                             }
-                            input.force_current_scroll_area = false;
                         });
 
                         state.scroll_stuck_to_end[d] = false;
diff --git a/crates/egui/src/frame_state.rs b/crates/egui/src/frame_state.rs
index 87074c2a725..fb6d785025f 100644
--- a/crates/egui/src/frame_state.rs
+++ b/crates/egui/src/frame_state.rs
@@ -38,9 +38,12 @@ pub(crate) struct FrameState {
     /// Initialized to `None` at the start of each frame.
     pub(crate) tooltip_state: Option<TooltipFrameState>,
 
-    /// horizontal, vertical
+    /// The current scroll area should scroll to this range (horizontal, vertical).
     pub(crate) scroll_target: [Option<(Rangef, Option<Align>)>; 2],
 
+    /// The current scroll area should scroll by this much (horizontal, vertical).
+    pub(crate) scroll_delta: [Option<f32>; 2],
+
     #[cfg(feature = "accesskit")]
     pub(crate) accesskit_state: Option<AccessKitFrameState>,
 
@@ -63,6 +66,7 @@ impl Default for FrameState {
             used_by_panels: Rect::NAN,
             tooltip_state: None,
             scroll_target: [None, None],
+            scroll_delta: [None, None],
             #[cfg(feature = "accesskit")]
             accesskit_state: None,
             highlight_this_frame: Default::default(),
@@ -84,6 +88,7 @@ impl FrameState {
             used_by_panels,
             tooltip_state,
             scroll_target,
+            scroll_delta,
             #[cfg(feature = "accesskit")]
             accesskit_state,
             highlight_this_frame,
@@ -99,6 +104,7 @@ impl FrameState {
         *used_by_panels = Rect::NOTHING;
         *tooltip_state = None;
         *scroll_target = [None, None];
+        *scroll_delta = [None, None];
 
         #[cfg(debug_assertions)]
         {
diff --git a/crates/egui/src/input_state.rs b/crates/egui/src/input_state.rs
index ff6a1165e31..9c6103e0a54 100644
--- a/crates/egui/src/input_state.rs
+++ b/crates/egui/src/input_state.rs
@@ -70,10 +70,6 @@ pub struct InputState {
     /// at the end of the frame this will be zero if a scroll-area consumed the delta.
     pub smooth_scroll_delta: Vec2,
 
-    /// Force the current scroll area to consume the [Self::smooth_scroll_delta], independent of the focus / mouse position.
-    /// This is used when using [crate::Ui::scroll_with_delta] to scroll the current scroll area.
-    pub(crate) force_current_scroll_area: bool,
-
     /// Zoom scale factor this frame (e.g. from ctrl-scroll or pinch gesture).
     ///
     /// * `zoom = 1`: no change.
@@ -158,7 +154,6 @@ impl Default for InputState {
             unprocessed_scroll_delta: Vec2::ZERO,
             raw_scroll_delta: Vec2::ZERO,
             smooth_scroll_delta: Vec2::ZERO,
-            force_current_scroll_area: false,
             zoom_factor_delta: 1.0,
             screen_rect: Rect::from_min_size(Default::default(), vec2(10_000.0, 10_000.0)),
             pixels_per_point: 1.0,
@@ -260,7 +255,6 @@ impl InputState {
             unprocessed_scroll_delta,
             raw_scroll_delta,
             smooth_scroll_delta,
-            force_current_scroll_area: false,
             zoom_factor_delta,
             screen_rect,
             pixels_per_point,
@@ -1119,7 +1113,6 @@ impl InputState {
             unprocessed_scroll_delta,
             raw_scroll_delta,
             smooth_scroll_delta,
-            force_current_scroll_area,
 
             zoom_factor_delta,
             screen_rect,
@@ -1164,9 +1157,6 @@ impl InputState {
         ui.label(format!(
             "smooth_scroll_delta: {smooth_scroll_delta:?} points"
         ));
-        ui.label(format!(
-            "force_current_scroll_area: {force_current_scroll_area}"
-        ));
         ui.label(format!("zoom_factor_delta: {zoom_factor_delta:4.2}x"));
         ui.label(format!("screen_rect: {screen_rect:?} points"));
         ui.label(format!(
diff --git a/crates/egui/src/ui.rs b/crates/egui/src/ui.rs
index ac14cfe3aa1..5a5b80a7a36 100644
--- a/crates/egui/src/ui.rs
+++ b/crates/egui/src/ui.rs
@@ -1091,9 +1091,8 @@ impl Ui {
     /// # });
     /// ```
     pub fn scroll_with_delta(&self, delta: Vec2) {
-        self.ctx().input_mut(|input| {
-            input.smooth_scroll_delta += delta;
-            input.force_current_scroll_area = true;
+        self.ctx().frame_state_mut(|state| {
+            state.scroll_delta = [Some(delta.x), Some(delta.y)];
         });
     }
 }
diff --git a/crates/egui_demo_lib/src/demo/scrolling.rs b/crates/egui_demo_lib/src/demo/scrolling.rs
index d7bee754c5b..6e2c1d0128f 100644
--- a/crates/egui_demo_lib/src/demo/scrolling.rs
+++ b/crates/egui_demo_lib/src/demo/scrolling.rs
@@ -294,7 +294,7 @@ impl super::View for ScrollTo {
             scroll_top |= ui.button("Scroll to top").clicked();
             scroll_bottom |= ui.button("Scroll to bottom").clicked();
             if ui.button("Scroll down by 64px").clicked() {
-                scroll_delta = Some(Vec2::new(0.0, -64.0));
+                scroll_delta = Some(Vec2::new(0.0, 64.0));
             }
         });
 

From 6e735324b60947c538a03b0989babac02494e840 Mon Sep 17 00:00:00 2001
From: Lucas Meurer <lucasmeurer96@gmail.com>
Date: Mon, 22 Apr 2024 16:09:13 +0200
Subject: [PATCH 3/7] Change scroll_delta to be Vec2

---
 crates/egui/src/containers/scroll_area.rs | 18 ++++++++++--------
 crates/egui/src/frame_state.rs            |  8 ++++----
 crates/egui/src/ui.rs                     |  2 +-
 3 files changed, 15 insertions(+), 13 deletions(-)

diff --git a/crates/egui/src/containers/scroll_area.rs b/crates/egui/src/containers/scroll_area.rs
index b3a4e6b9f64..855ba5dc582 100644
--- a/crates/egui/src/containers/scroll_area.rs
+++ b/crates/egui/src/containers/scroll_area.rs
@@ -782,15 +782,21 @@ impl Prepared {
 
         let content_size = content_ui.min_size();
 
+        let scroll_delta = content_ui
+            .ctx()
+            .frame_state_mut(|state| std::mem::take(&mut state.scroll_delta));
+
         for d in 0..2 {
+            let mut delta = scroll_delta[d];
+
             // We always take both scroll targets regardless of which scroll axes are enabled. This
             // is to avoid them leaking to other scroll areas.
-            let (scroll_target, scroll_delta) = content_ui.ctx().frame_state_mut(|state| {
-                (state.scroll_target[d].take(), state.scroll_delta[d].take())
-            });
+            let scroll_target = content_ui
+                .ctx()
+                .frame_state_mut(|state| state.scroll_target[d].take());
 
             if scroll_enabled[d] {
-                let mut delta = if let Some((target_range, align)) = scroll_target {
+                delta += if let Some((target_range, align)) = scroll_target {
                     let min = content_ui.min_rect().min[d];
                     let clip_rect = content_ui.clip_rect();
                     let visible_range = min..=min + clip_rect.size()[d];
@@ -821,10 +827,6 @@ impl Prepared {
                     0.0
                 };
 
-                if let Some(scroll_delta) = scroll_delta {
-                    delta += scroll_delta;
-                }
-
                 if delta != 0.0 {
                     let target_offset = state.offset[d] + delta;
 
diff --git a/crates/egui/src/frame_state.rs b/crates/egui/src/frame_state.rs
index fb6d785025f..3ed1a3691de 100644
--- a/crates/egui/src/frame_state.rs
+++ b/crates/egui/src/frame_state.rs
@@ -41,8 +41,8 @@ pub(crate) struct FrameState {
     /// The current scroll area should scroll to this range (horizontal, vertical).
     pub(crate) scroll_target: [Option<(Rangef, Option<Align>)>; 2],
 
-    /// The current scroll area should scroll by this much (horizontal, vertical).
-    pub(crate) scroll_delta: [Option<f32>; 2],
+    /// The current scroll area should scroll by this much.
+    pub(crate) scroll_delta: Vec2,
 
     #[cfg(feature = "accesskit")]
     pub(crate) accesskit_state: Option<AccessKitFrameState>,
@@ -66,7 +66,7 @@ impl Default for FrameState {
             used_by_panels: Rect::NAN,
             tooltip_state: None,
             scroll_target: [None, None],
-            scroll_delta: [None, None],
+            scroll_delta: Vec2::default(),
             #[cfg(feature = "accesskit")]
             accesskit_state: None,
             highlight_this_frame: Default::default(),
@@ -104,7 +104,7 @@ impl FrameState {
         *used_by_panels = Rect::NOTHING;
         *tooltip_state = None;
         *scroll_target = [None, None];
-        *scroll_delta = [None, None];
+        *scroll_delta = Vec2::default();
 
         #[cfg(debug_assertions)]
         {
diff --git a/crates/egui/src/ui.rs b/crates/egui/src/ui.rs
index 5a5b80a7a36..65cb2c9401f 100644
--- a/crates/egui/src/ui.rs
+++ b/crates/egui/src/ui.rs
@@ -1092,7 +1092,7 @@ impl Ui {
     /// ```
     pub fn scroll_with_delta(&self, delta: Vec2) {
         self.ctx().frame_state_mut(|state| {
-            state.scroll_delta = [Some(delta.x), Some(delta.y)];
+            state.scroll_delta = delta;
         });
     }
 }

From cbcccd2f621da00630bbde049bb4476e5121989b Mon Sep 17 00:00:00 2001
From: Lucas Meurer <lucasmeurer96@gmail.com>
Date: Mon, 27 May 2024 17:16:42 +0200
Subject: [PATCH 4/7] Combine scroll delta when calling scroll_with_delta
 multiple times per frame

---
 crates/egui/src/ui.rs | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/crates/egui/src/ui.rs b/crates/egui/src/ui.rs
index 65cb2c9401f..ab8ace57e1b 100644
--- a/crates/egui/src/ui.rs
+++ b/crates/egui/src/ui.rs
@@ -1073,6 +1073,8 @@ impl Ui {
     /// A positive Y-value indicates the content is being moved down,
     /// as when swiping down on a touch-screen or track-pad with natural scrolling.
     ///
+    /// If this is called multiple times per frame for the same ScrollArea, the deltas will be combined.
+    ///
     /// /// See also: [`Response::scroll_to_me`], [`Ui::scroll_to_rect`], [`Ui::scroll_to_cursor`]
     ///
     /// ```
@@ -1092,7 +1094,7 @@ impl Ui {
     /// ```
     pub fn scroll_with_delta(&self, delta: Vec2) {
         self.ctx().frame_state_mut(|state| {
-            state.scroll_delta = delta;
+            state.scroll_delta += delta;
         });
     }
 }

From 6c58dbe578e6ecf9d12dc29e70d3dec543493b0f Mon Sep 17 00:00:00 2001
From: Lucas Meurer <lucasmeurer96@gmail.com>
Date: Mon, 27 May 2024 17:20:09 +0200
Subject: [PATCH 5/7] Fix scroll_with_delta behaviour being inverted

---
 crates/egui/src/containers/scroll_area.rs  | 3 ++-
 crates/egui/src/frame_state.rs             | 8 ++++++++
 crates/egui/src/ui.rs                      | 2 +-
 crates/egui_demo_lib/src/demo/scrolling.rs | 2 +-
 4 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/crates/egui/src/containers/scroll_area.rs b/crates/egui/src/containers/scroll_area.rs
index 855ba5dc582..3bdac533ba2 100644
--- a/crates/egui/src/containers/scroll_area.rs
+++ b/crates/egui/src/containers/scroll_area.rs
@@ -787,7 +787,8 @@ impl Prepared {
             .frame_state_mut(|state| std::mem::take(&mut state.scroll_delta));
 
         for d in 0..2 {
-            let mut delta = scroll_delta[d];
+            // FrameState::scroll_delta is inverted from the way we apply the delta, so we need to negate it.
+            let mut delta = -scroll_delta[d];
 
             // We always take both scroll targets regardless of which scroll axes are enabled. This
             // is to avoid them leaking to other scroll areas.
diff --git a/crates/egui/src/frame_state.rs b/crates/egui/src/frame_state.rs
index 3ed1a3691de..5b7de3d10b3 100644
--- a/crates/egui/src/frame_state.rs
+++ b/crates/egui/src/frame_state.rs
@@ -42,6 +42,14 @@ pub(crate) struct FrameState {
     pub(crate) scroll_target: [Option<(Rangef, Option<Align>)>; 2],
 
     /// The current scroll area should scroll by this much.
+    ///
+    /// The delta dictates how the _content_ should move.
+    ///
+    /// A positive X-value indicates the content is being moved right,
+    /// as when swiping right on a touch-screen or track-pad with natural scrolling.
+    ///
+    /// A positive Y-value indicates the content is being moved down,
+    /// as when swiping down on a touch-screen or track-pad with natural scrolling.
     pub(crate) scroll_delta: Vec2,
 
     #[cfg(feature = "accesskit")]
diff --git a/crates/egui/src/ui.rs b/crates/egui/src/ui.rs
index ab8ace57e1b..e34a3ad1cb9 100644
--- a/crates/egui/src/ui.rs
+++ b/crates/egui/src/ui.rs
@@ -1073,7 +1073,7 @@ impl Ui {
     /// A positive Y-value indicates the content is being moved down,
     /// as when swiping down on a touch-screen or track-pad with natural scrolling.
     ///
-    /// If this is called multiple times per frame for the same ScrollArea, the deltas will be combined.
+    /// If this is called multiple times per frame for the same [`ScrollArea`], the deltas will be combined.
     ///
     /// /// See also: [`Response::scroll_to_me`], [`Ui::scroll_to_rect`], [`Ui::scroll_to_cursor`]
     ///
diff --git a/crates/egui_demo_lib/src/demo/scrolling.rs b/crates/egui_demo_lib/src/demo/scrolling.rs
index 6e2c1d0128f..d7bee754c5b 100644
--- a/crates/egui_demo_lib/src/demo/scrolling.rs
+++ b/crates/egui_demo_lib/src/demo/scrolling.rs
@@ -294,7 +294,7 @@ impl super::View for ScrollTo {
             scroll_top |= ui.button("Scroll to top").clicked();
             scroll_bottom |= ui.button("Scroll to bottom").clicked();
             if ui.button("Scroll down by 64px").clicked() {
-                scroll_delta = Some(Vec2::new(0.0, 64.0));
+                scroll_delta = Some(Vec2::new(0.0, -64.0));
             }
         });
 

From f8c9592a431ab7d538b2177dbd333be70fb535fa Mon Sep 17 00:00:00 2001
From: lucasmerlin <lucasmeurer96@gmail.com>
Date: Mon, 27 May 2024 23:12:59 +0200
Subject: [PATCH 6/7] Apply suggestions from code review

Co-authored-by: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>
---
 crates/egui/src/ui.rs                      | 2 +-
 crates/egui_demo_lib/src/demo/scrolling.rs | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/crates/egui/src/ui.rs b/crates/egui/src/ui.rs
index e34a3ad1cb9..fac5ea2b60d 100644
--- a/crates/egui/src/ui.rs
+++ b/crates/egui/src/ui.rs
@@ -1073,7 +1073,7 @@ impl Ui {
     /// A positive Y-value indicates the content is being moved down,
     /// as when swiping down on a touch-screen or track-pad with natural scrolling.
     ///
-    /// If this is called multiple times per frame for the same [`ScrollArea`], the deltas will be combined.
+    /// If this is called multiple times per frame for the same [`ScrollArea`], the deltas will be summed.
     ///
     /// /// See also: [`Response::scroll_to_me`], [`Ui::scroll_to_rect`], [`Ui::scroll_to_cursor`]
     ///
diff --git a/crates/egui_demo_lib/src/demo/scrolling.rs b/crates/egui_demo_lib/src/demo/scrolling.rs
index d7bee754c5b..cd9dd13ebf5 100644
--- a/crates/egui_demo_lib/src/demo/scrolling.rs
+++ b/crates/egui_demo_lib/src/demo/scrolling.rs
@@ -294,7 +294,7 @@ impl super::View for ScrollTo {
             scroll_top |= ui.button("Scroll to top").clicked();
             scroll_bottom |= ui.button("Scroll to bottom").clicked();
             if ui.button("Scroll down by 64px").clicked() {
-                scroll_delta = Some(Vec2::new(0.0, -64.0));
+                scroll_delta = Some(64.0 * Vec2::UP); // move contents up
             }
         });
 

From f65eb519a62f9a13909cae728d36109ee0b2bef3 Mon Sep 17 00:00:00 2001
From: Lucas Meurer <lucasmeurer96@gmail.com>
Date: Mon, 27 May 2024 23:27:30 +0200
Subject: [PATCH 7/7] Improve scroll by example

---
 crates/egui_demo_lib/src/demo/scrolling.rs | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/crates/egui_demo_lib/src/demo/scrolling.rs b/crates/egui_demo_lib/src/demo/scrolling.rs
index cd9dd13ebf5..71d47f9d84c 100644
--- a/crates/egui_demo_lib/src/demo/scrolling.rs
+++ b/crates/egui_demo_lib/src/demo/scrolling.rs
@@ -236,6 +236,7 @@ struct ScrollTo {
     track_item: usize,
     tack_item_align: Option<Align>,
     offset: f32,
+    delta: f32,
 }
 
 impl Default for ScrollTo {
@@ -244,6 +245,7 @@ impl Default for ScrollTo {
             track_item: 25,
             tack_item_align: Some(Align::Center),
             offset: 0.0,
+            delta: 64.0,
         }
     }
 }
@@ -293,8 +295,19 @@ impl super::View for ScrollTo {
         ui.horizontal(|ui| {
             scroll_top |= ui.button("Scroll to top").clicked();
             scroll_bottom |= ui.button("Scroll to bottom").clicked();
-            if ui.button("Scroll down by 64px").clicked() {
-                scroll_delta = Some(64.0 * Vec2::UP); // move contents up
+        });
+
+        ui.horizontal(|ui| {
+            ui.label("Scroll by");
+            DragValue::new(&mut self.delta)
+                .speed(1.0)
+                .suffix("px")
+                .ui(ui);
+            if ui.button("⬇").clicked() {
+                scroll_delta = Some(self.delta * Vec2::UP); // scroll down (move contents up)
+            }
+            if ui.button("⬆").clicked() {
+                scroll_delta = Some(self.delta * Vec2::DOWN); // scroll up (move contents down)
             }
         });