diff --git a/Sources/Backend/GTK4/Rendering/GTKViewHost.swift b/Sources/Backend/GTK4/Rendering/GTKViewHost.swift
index 2a7f15c..8d0164a 100644
--- a/Sources/Backend/GTK4/Rendering/GTKViewHost.swift
+++ b/Sources/Backend/GTK4/Rendering/GTKViewHost.swift
@@ -236,19 +236,46 @@ public class GTKViewHost: AnyViewHost, DependencyTrackingHost {
         observationDidFire = false
         lock.unlock()
 
-        // --- Narrow mutation path: try text/color in-place update ---
-        // Skipped when withObservationTracking's onChange fired — the narrow
-        // path returns without re-running body under withObservationTracking,
-        // which would leave @Observable subscriptions dead after the first
-        // change. Fall through to the full rebuild so observation re-registers.
-        if !fromObservation,
-           let describeBody = describeBody,
+        // --- Narrow mutation path: try text/color/canvas in-place update ---
+        // Applied for both @State- and @Observable-driven changes. A full
+        // rebuild tears down the widget tree, which cancels any in-flight
+        // gesture (e.g. a drag on a Canvas knob); the narrow path mutates in
+        // place and preserves it. For an @Observable change the describe pass
+        // below is run under `withObservationTracking`, so re-reading the
+        // observed properties re-registers the one-shot subscription — the same
+        // re-registration the full rebuild gets from `buildBodyWithTracking`,
+        // without the teardown. If the change is not narrow-applicable we fall
+        // through to the full rebuild, which re-registers observation as before.
+        if let describeBody = describeBody,
            let oldRetained = lastRetainedDescriptor,
            let oldExecutor = retainedExecutor {
 
             let previousEnv = getCurrentEnvironment()
             installRebuildEnvironment()
-            let described = gtkDescribeCapturingCanvasPayloads(describeBody)
+            let described: (descriptor: GTK4DescriptorNode, canvasPayloads: [GTK4CanvasPayload])
+            if fromObservation {
+                #if canImport(Observation)
+                if #available(macOS 14.0, iOS 17.0, *) {
+                    var captured: (descriptor: GTK4DescriptorNode, canvasPayloads: [GTK4CanvasPayload])!
+                    withObservationTracking {
+                        captured = gtkDescribeCapturingCanvasPayloads(describeBody)
+                    } onChange: { [weak self] in
+                        guard let self else { return }
+                        self.lock.lock()
+                        self.observationDidFire = true
+                        self.lock.unlock()
+                        self.scheduleRebuild()
+                    }
+                    described = captured
+                } else {
+                    described = gtkDescribeCapturingCanvasPayloads(describeBody)
+                }
+                #else
+                described = gtkDescribeCapturingCanvasPayloads(describeBody)
+                #endif
+            } else {
+                described = gtkDescribeCapturingCanvasPayloads(describeBody)
+            }
             setCurrentEnvironment(previousEnv)
 
             let newIdentified = gtkIdentifyDescriptorTree(described.descriptor)