1 files changed, 13 insertions, 4 deletions

diff --git a/src/components/main/layout/flow.rs b/src/components/main/layout/flow.rs
index 9abd29ab934..953a008ad0a 100644
--- a/src/components/main/layout/flow.rs
+++ b/src/components/main/layout/flow.rs
@@ -6,20 +6,20 @@
 //! layout constraints to obtain positions and display attributes of tree nodes. Positions are
 //! computed in several tree traversals driven by the fundamental data dependencies required by
 /// inline and block layout.
-/// 
+///
 /// Flows are interior nodes in the layout tree and correspond closely to *flow contexts* in the
 /// CSS specification. Flows are responsible for positioning their child flow contexts and boxes.
 /// Flows have purpose-specific fields, such as auxiliary line box structs, out-of-flow child
 /// lists, and so on.
 ///
 /// Currently, the important types of flows are:
-/// 
+///
 /// * `BlockFlow`: A flow that establishes a block context. It has several child flows, each of
 ///   which are positioned according to block formatting context rules (CSS block boxes). Block
 ///   flows also contain a single `GenericBox` to represent their rendered borders, padding, etc.
 ///   The BlockFlow at the root of the tree has special behavior: it stretches to the boundaries of
 ///   the viewport.
-///   
+///
 /// * `InlineFlow`: A flow that establishes an inline context. It has a flat list of child
 ///   boxes/flows that are subject to inline layout and line breaking and structs to represent
 ///   line breaks and mapping to CSS boxes, for the purpose of handling `getClientRects()` and
@@ -698,6 +698,11 @@ impl<'a> MutableFlowUtils for &'a mut Flow {
         mut_base(self).overflow = overflow
     }
 
+    /// Push display items for current flow and its children onto `list`.
+    ///
+    /// For InlineFlow, add display items for all its boxes onto list`.
+    /// For BlockFlow, add a ClipDisplayItemClass for itself and its children,
+    /// plus any other display items like border.
     fn build_display_lists<E:ExtraDisplayListData>(
                           self,
                           builder: &DisplayListBuilder,
@@ -723,6 +728,11 @@ impl<'a> MutableFlowUtils for &'a mut Flow {
         }
 
         let mut child_lists = Some(child_lists.unwrap());
+        // Find parent ClipDisplayItemClass and push all child display items
+        // under it
+        // FIXME: Once we have children for InlineFlow, this might lead to
+        // children display items being pushed under the ClipDisplayItemClass
+        // created by the last box of the InlineFlow. Fix the logic.
         lists.with_mut(|lists| {
             let mut child_lists = child_lists.take_unwrap();
             let result = lists.lists[index].list.mut_rev_iter().position(|item| {
@@ -848,4 +858,3 @@ impl FlowLeafSet {
         self.set.iter()
     }
 }
-