diff --git a/Src/Common/Controls/DetailControls/DataTree.cs b/Src/Common/Controls/DetailControls/DataTree.cs
index f05bd108c1..9303b46973 100644
--- a/Src/Common/Controls/DetailControls/DataTree.cs
+++ b/Src/Common/Controls/DetailControls/DataTree.cs
@@ -553,8 +553,11 @@ public void PropChanged(int hvo, int tag, int ivMin, int cvIns, int cvDel)
 			//	return;
 			if (m_monitoredProps.Contains(Tuple.Create(hvo, tag)))
 			{
-				RefreshList(false);
-				OnFocusFirstPossibleSlice(null);
+				// If we call RefreshList now, it causes a crash in the invoker
+				// because some slice data structures that are being used by the invoker
+				// get disposed by RefreshList (LT-21980, LT-22011).  So we postpone calling
+				// RefreshList until the work is done.
+				this.BeginInvoke(new Action(PostponedRefreshList));
 			}
 			// Note, in LinguaLinks import we don't have an action handler when we hit this.
 			else if (m_cache.DomainDataByFlid.GetActionHandler() != null && m_cache.DomainDataByFlid.GetActionHandler().IsUndoOrRedoInProgress)
@@ -581,6 +584,15 @@ public void PropChanged(int hvo, int tag, int ivMin, int cvIns, int cvDel)
 			}
 		}
 
+		private void PostponedRefreshList()
+		{
+			if (!IsDisposed)
+			{
+				RefreshList(false);
+				OnFocusFirstPossibleSlice(null);
+			}
+		}
+
 		/// <summary></summary>
 		public Mediator Mediator
 		{
diff --git a/Src/Common/Controls/DetailControls/MSAReferenceComboBoxSlice.cs b/Src/Common/Controls/DetailControls/MSAReferenceComboBoxSlice.cs
index eefb2a0785..4c64cfc413 100644
--- a/Src/Common/Controls/DetailControls/MSAReferenceComboBoxSlice.cs
+++ b/Src/Common/Controls/DetailControls/MSAReferenceComboBoxSlice.cs
@@ -99,8 +99,6 @@ public override Mediator Mediator
 				m_MSAPopupTreeManager = new MSAPopupTreeManager(m_tree, m_cache, list,
 					m_tree.WritingSystemCode, true, m_mediator, m_propertyTable,
 					m_propertyTable.GetValue<Form>("window"));
-				m_MSAPopupTreeManager.BeforeChange += m_MSAPopupTreeManager_BeforeChange;
-				m_MSAPopupTreeManager.AfterChange += m_MSAPopupTreeManager_AfterChange;
 				m_MSAPopupTreeManager.AfterSelect += m_MSAPopupTreeManager_AfterSelect;
 				m_MSAPopupTreeManager.Sense = m_obj as ILexSense;
 				m_MSAPopupTreeManager.PersistenceProvider = m_persistProvider;
@@ -225,33 +223,6 @@ protected override void UpdateDisplayFromDatabase()
 			// What do we need to do here, if anything?
 		}
 
-		public void m_MSAPopupTreeManager_BeforeChange(object sender, TreeViewEventArgs e)
-		{
-			if (!ContainingDataTree.DoNotRefresh)
-			{
-				// Postpone refreshing the screen until m_MSAPopupTreeManager_AfterChange (LT-21980).
-				ContainingDataTree.DoNotRefresh = true;
-				m_forceRefresh = true;
-			}
-		}
-
-		public void m_MSAPopupTreeManager_AfterChange(object sender, TreeViewEventArgs e)
-		{
-			if (m_forceRefresh)
-			{
-				m_forceRefresh = false;
-				// We can't call RefreshDataTree directly,
-				// since that will cause Windows to crash accessing a disposed object.
-				// So, we queue it on the UI thread instead.
-				this.BeginInvoke(new Action(RefreshDataTree));
-			}
-		}
-
-		public void RefreshDataTree()
-		{
-			ContainingDataTree.DoNotRefresh = false;
-		}
-
 		private void m_MSAPopupTreeManager_AfterSelect(object sender, TreeViewEventArgs e)
 		{
 			// unless we get a mouse click or simulated mouse click (e.g. by ENTER or TAB),
diff --git a/Src/LexText/LexTextControls/MSAPopupTreeManager.cs b/Src/LexText/LexTextControls/MSAPopupTreeManager.cs
index 4ed27add30..b294d55807 100644
--- a/Src/LexText/LexTextControls/MSAPopupTreeManager.cs
+++ b/Src/LexText/LexTextControls/MSAPopupTreeManager.cs
@@ -44,9 +44,6 @@ public class MSAPopupTreeManager : PopupTreeManager
 
 		#region Events
 
-		public event TreeViewEventHandler BeforeChange;
-		public event TreeViewEventHandler AfterChange;
-
 		#endregion Events
 
 		/// <summary>
@@ -422,19 +419,11 @@ private bool EditExistingMsa()
 					m_sense.MorphoSyntaxAnalysisRA.Hvo, true, m_sEditGramFunc);
 				if (dlg.ShowDialog(ParentForm) == DialogResult.OK)
 				{
-					if (BeforeChange != null)
-					{
-						BeforeChange(this, null);
-					}
 					Cache.DomainDataByFlid.BeginUndoTask(String.Format(LexTextControls.ksUndoSetX, FieldName),
 						String.Format(LexTextControls.ksRedoSetX, FieldName));
 					m_sense.SandboxMSA = dlg.SandboxMSA;
 					Cache.DomainDataByFlid.EndUndoTask();
 					LoadPopupTree(m_sense.MorphoSyntaxAnalysisRA.Hvo);
-					if (AfterChange != null)
-					{
-						AfterChange(this, null);
-					}
 					return true;
 				}
 			}