diff --git a/HellionChat/Ui/StyleEngine/RowSurfaceScope.cs b/HellionChat/Ui/StyleEngine/RowSurfaceScope.cs
new file mode 100644
index 0000000..825e792
--- /dev/null
+++ b/HellionChat/Ui/StyleEngine/RowSurfaceScope.cs
@@ -0,0 +1,75 @@
+using System.Numerics;
+using Dalamud.Bindings.ImGui;
+
+namespace HellionChat.Ui.StyleEngine;
+
+// Draws a surface behind a row whose height is only known after the text has been
+// drawn. Text goes into channel 1, the fill into channel 0, and the merge puts
+// the fill underneath.
+//
+// Only needed on the frame after the height cache is dropped. Every other frame
+// the cached height is already correct -- a chat message does not change height
+// after its first measurement -- so the caller draws the fill directly and never
+// comes near this.
+//
+// Three things make draw channels sharp:
+//
+// Nesting a splitter into itself asserts, and Dalamud does not compile asserts
+// out. The user would get an error dialog, not a glitch. Hence the depth count.
+//
+// A forgotten merge is not a dropped frame, it is permanent: the commands stay
+// in the channel buffers and never reach the draw list, and the next frame's
+// split walks into the assert. Hence the finally.
+//
+// And the clip rect carries over on a channel switch, so the fill inherits
+// whatever was clipping the text.
+internal static class RowSurfaceScope
+{
+    [ThreadStatic]
+    private static int _depth;
+
+    [ThreadStatic]
+    private static ImDrawListPtr _drawList;
+
+    internal static bool IsActive => _depth > 0;
+
+    internal static Scope Push()
+    {
+        if (_depth == 0)
+        {
+            _drawList = ImGui.GetWindowDrawList();
+            _drawList.ChannelsSplit(2);
+            // Foreground is the resting state: everything that is not explicitly
+            // painting a surface draws where it expects to.
+            _drawList.ChannelsSetCurrent(1);
+        }
+
+        _depth++;
+        return new Scope();
+    }
+
+    // Paints into the background channel and returns immediately to the
+    // foreground, so a caller can never leave the channel switched.
+    internal static void Fill(Vector2 min, Vector2 max, uint abgr, float rounding)
+    {
+        if (!IsActive)
+            return;
+
+        _drawList.ChannelsSetCurrent(0);
+        _drawList.AddRectFilled(min, max, abgr, rounding);
+        _drawList.ChannelsSetCurrent(1);
+    }
+
+    internal readonly struct Scope : IDisposable
+    {
+        public void Dispose()
+        {
+            _depth--;
+            if (_depth > 0)
+                return;
+
+            _drawList.ChannelsMerge();
+            _drawList = default;
+        }
+    }
+}