From deab6e65b81503046a5b6c72f6574d1706347622 Mon Sep 17 00:00:00 2001
From: paul-dev8 <paulnexus85@gmail.com>
Date: Sun, 22 Mar 2026 22:04:12 -0500
Subject: [PATCH] Update tree.rs

In `src/wayland/compositor/tree.rs`, `PrivateSurfaceData::commit()`, when processing children:

```rust
for child in children {
    let is_child_sync = ...;

    if !is_sync && is_child_sync {
        // Sync child with non-sync parent: commit child tree
        Self::commit_sync_surface_tree(&child, ...);
    } else if is_sync || is_child_sync {
        // Sync child: merge into parent's transaction
        let child_tx = std::mem::take(&mut child_data.pending_transaction);
        child_tx.merge_into(&my_data.pending_transaction);
        child_data.current_txid.0 = child_data.current_txid.0.wrapping_add(1);
    }
    // BUG: No handling for desync child with non-sync parent!
    // SubsurfaceCachedState.pending().location is never committed.
}
```

When both parent and child are desync (the common case for Chrome), neither branch executes. The child's `SubsurfaceCachedState` pending location (set by `set_position`) is never moved to the current state.
---
 src/wayland/compositor/tree.rs | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/src/wayland/compositor/tree.rs b/src/wayland/compositor/tree.rs
index 798bf356b649..e7778c906ca6 100644
--- a/src/wayland/compositor/tree.rs
+++ b/src/wayland/compositor/tree.rs
@@ -305,7 +305,16 @@ impl PrivateSurfaceData {
                 let child_tx = std::mem::take(&mut child_data.pending_transaction);
                 child_tx.merge_into(&my_data.pending_transaction);
                 child_data.current_txid.0 = child_data.current_txid.0.wrapping_add(1);
-            }
+             } else {
++                // Desync child with non-sync parent: per Wayland protocol spec,
++                // wl_subsurface.set_position "is applied when the parent surface's
++                // wl_surface.commit is called." Commit with None to apply pending
++                // state directly to current (bypassing the transaction queue).
++                // This is safe because desync subsurface buffer state is already
++                // applied on the child's own commit — only SubsurfaceCachedState
++                // (position) has pending changes from set_position. (smithay#1894)
++                child_data.public_data.cached_state.commit(None, dh);
+             }
         }
         my_data
             .pending_transaction