Small Fixes for 21.1 or newer

Editor/ImageSequencer/ImageSequencer.GUI.cs

         private ReorderableList m_InputFramesReorderableList;
         private ReorderableList m_ProcessorsReorderableList;
         private Vector2 m_OptionsViewScroll = Vector2.zero;
-        private Vector2 m_MinimumSize;
+
         private SidePanelMode m_SidePanelViewMode = 0;
         private bool m_Dirty = true;
         private bool m_NeedRedraw = false;
-            minSize = m_MinimumSize;
-
             if(m_Splitter == null)
             {
                 m_Splitter = new Splitter(360, DrawEditPanelGUI, DrawCanvasGUI, Splitter.SplitLockMode.LeftMinMax, new Vector2(320.0f, 480.0f));
 
         public void OnGUI()
         {
-            if(EditorGUIUtility.isProSkin)
-                titleContent = styles.proTitle;
-            else
-                titleContent = styles.title;
-            m_MinimumSize = new Vector2(880, 320);
-
             InitializeGUI();
 
             if(m_CurrentAsset == null)

Editor/ImageSequencer/ImageSequencer.cs

 
         void OnEnable()
         {
+            if (EditorGUIUtility.isProSkin)
+                titleContent = styles.proTitle;
+            else
+                titleContent = styles.title;
+
             m_ProcessorDataProvider = null;
 
             if(Selection.activeObject != null && Selection.activeObject is ImageSequence)
                 LoadAsset(m_CurrentAsset);
                 DefaultView();
             }
+
+            minSize = new Vector2(880, 320);
 
         }
 
                 // Construct the RList
                 if (m_CurrentAsset.inheritSettingsReference == null)
                 {
+#if UNITY_2020_1_OR_NEWER
+                    m_ProcessorsReorderableList = new ReorderableList(m_CurrentAsset.processorInfos, typeof(ProcessorInfo), true, false, true, true);
+#else
+#endif
                     m_ProcessorsReorderableList.onAddCallback = ShowAddProcessorMenu;
                     m_ProcessorsReorderableList.onRemoveCallback = MenuRemoveProcessor;
                     m_ProcessorsReorderableList.onReorderCallback = ReorderProcessor;