Avoid saved state being discarded when message list is modified

res/layout/message_list_fragment.xml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
-<com.handmark.pulltorefresh.library.PullToRefreshListView
+<com.fsck.k9.view.K9PullToRefreshListView
     xmlns:android="http://schemas.android.com/apk/res/android"
     android:id="@+id/message_list"
     android:layout_width="fill_parent"

src/com/fsck/k9/view/K9PullToRefreshListView.java

@@ -0,0 +1,33 @@
+package com.fsck.k9.view;
+
+import android.content.Context;
+import android.os.Parcelable;
+import android.util.AttributeSet;
+import android.widget.ListView;
+
+import com.handmark.pulltorefresh.library.PullToRefreshListView;
+
+
+public class K9PullToRefreshListView extends PullToRefreshListView {
+
+    public K9PullToRefreshListView(Context context, AttributeSet attrs) {
+        super(context, attrs);
+    }
+
+    @Override
+    protected ListView createListView(Context context, AttributeSet attrs) {
+        return new ListView(context, attrs) {
+            @Override
+            public void onRestoreInstanceState(Parcelable state) {
+                super.onRestoreInstanceState(state);
+
+                /*
+                 * Force the list view to apply the restored state instantly instead of
+                 * asynchronously, so potential data changes (which in turn cause an internal
+                 * position save/restore) don't overwrite our saved position.
+                 */
+                layoutChildren();
+            }
+        };
+    }
+}