added scroll offset to ComputedNode and update it in ui_layout_system

crates/bevy_ui/src/layout/mod.rs

@@ -333,6 +333,8 @@ with UI components as a child of an entity without UI components, your UI layout
 
             let physical_scroll_position = clamped_scroll_position.floor();
 
+            node.bypass_change_detection().scroll_offset = physical_scroll_position;
+
             for child_uinode in ui_children.iter_ui_children(entity) {
                 update_uinode_geometry_recursive(
                     commands,

crates/bevy_ui/src/ui_node.rs

@@ -46,6 +46,10 @@ pub struct ComputedNode {
     ///
     /// Automatically calculated by [`super::layout::ui_layout_system`].
     pub scrollbar_size: Vec2,
+    /// Offset of scrolled content
+    ///
+    /// Automatically calculated by [`super::layout::ui_layout_system`].
+    pub scroll_offset: Vec2,
     /// The width of this node's outline.
     /// If this value is `Auto`, negative or `0.` then no outline will be rendered.
     /// Outline updates bypass change detection.
@@ -310,6 +314,7 @@ impl ComputedNode {
         size: Vec2::ZERO,
         content_size: Vec2::ZERO,
         scrollbar_size: Vec2::ZERO,
+        scroll_offset: Vec2::ZERO,
         outline_width: 0.,
         outline_offset: 0.,
         unrounded_size: Vec2::ZERO,