From 89c74603643e6adbda69cf544d04c31ba1469ee9 Mon Sep 17 00:00:00 2001
From: Andrei Gorelov <2652045@gmail.com>
Date: Tue, 24 Mar 2026 16:34:06 +0300
Subject: [PATCH 1/2] =?UTF-8?q?Fix=20ConcurrentModificationException=20in?=
 =?UTF-8?q?=20AlphaTabRenderSurface=20placeholders=20list=C2=A0?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../alphaTab/platform/android/AlphaTabRenderSurface.kt    | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/packages/kotlin/src/android/src/main/java/alphaTab/platform/android/AlphaTabRenderSurface.kt b/packages/kotlin/src/android/src/main/java/alphaTab/platform/android/AlphaTabRenderSurface.kt
index a5e71229e..0ff15e381 100644
--- a/packages/kotlin/src/android/src/main/java/alphaTab/platform/android/AlphaTabRenderSurface.kt
+++ b/packages/kotlin/src/android/src/main/java/alphaTab/platform/android/AlphaTabRenderSurface.kt
@@ -12,6 +12,7 @@ import android.widget.ScrollView
 import java.io.Closeable
 import java.lang.RuntimeException
 import kotlin.contracts.ExperimentalContracts
+import java.util.concurrent.CopyOnWriteArrayList
 
 @ExperimentalUnsignedTypes
 @ExperimentalContracts
@@ -44,7 +45,7 @@ internal class RenderPlaceholder(public var result: RenderFinishedEventArgs) : C
 @ExperimentalContracts
 internal class AlphaTabRenderSurface(context: Context, attributeSet: AttributeSet) :
     View(context, attributeSet), View.OnScrollChangeListener {
-    private val _placeholders: ArrayList<RenderPlaceholder> = arrayListOf()
+    private val _placeholders: CopyOnWriteArrayList<RenderPlaceholder> = CopyOnWriteArrayList()
     private val _resultIdToIndex: ObjectDoubleMap<String> = ObjectDoubleMap()
 
     private var _totalWidth: Int = 0
@@ -65,11 +66,10 @@ internal class AlphaTabRenderSurface(context: Context, attributeSet: AttributeSe
 
     public fun clearPlaceholders() {
         _resultIdToIndex.clear()
-        val placeholder = _placeholders
-        for (p in placeholder) {
+        for (p in _placeholders) {
             p.close();
         }
-        placeholder.clear()
+        _placeholders.clear()
     }
 
     override fun onAttachedToWindow() {

From 821427db837577b278af3589f09a96bc208a84d7 Mon Sep 17 00:00:00 2001
From: Andrei Gorelov <2652045@gmail.com>
Date: Wed, 25 Mar 2026 20:12:38 +0300
Subject: [PATCH 2/2] Fix Android resize throttle to run on main thread
 (prevent BoundsLookup ConcurrentModificationException)

---
 .../src/android/src/main/java/alphaTab/EnvironmentPartials.kt   | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/kotlin/src/android/src/main/java/alphaTab/EnvironmentPartials.kt b/packages/kotlin/src/android/src/main/java/alphaTab/EnvironmentPartials.kt
index d3f534bcc..cc7fe85bf 100644
--- a/packages/kotlin/src/android/src/main/java/alphaTab/EnvironmentPartials.kt
+++ b/packages/kotlin/src/android/src/main/java/alphaTab/EnvironmentPartials.kt
@@ -39,7 +39,7 @@ internal class EnvironmentPartials {
             print("Screen Size: ${AndroidEnvironment.screenWidth}x${AndroidEnvironment.screenHeight}");
         }
 
-        private val throttleScope = CoroutineScope(Dispatchers.Default)
+        private val throttleScope = CoroutineScope(Dispatchers.Main)
         internal fun throttle(toThrottle: () -> Unit, delay: Double): () -> Unit {
             var job: Job? = null
             return {