diff --git a/mailnews/addrbook/src/nsAbView.cpp b/mailnews/addrbook/src/nsAbView.cpp
index 894e062ce3..66da0f648d 100644
--- a/mailnews/addrbook/src/nsAbView.cpp
+++ b/mailnews/addrbook/src/nsAbView.cpp
@@ -60,8 +60,10 @@ NS_IMETHODIMP nsAbView::ClearView()
 {
   mDirectory = nullptr;
   mAbViewListener = nullptr;
-  if (mTree)
-    mTree->SetView(nullptr);
+  if (mTree) {
+    IgnoredErrorResult rv2;
+    mTree->SetView(nullptr, mozilla::dom::CallerType::System, rv2);
+  }
   mTree = nullptr;
   mTreeSelection = nullptr;
 
@@ -105,8 +107,7 @@ nsresult nsAbView::RemoveCardAt(int32_t row)
 
   // This needs to happen after we remove the card, as RowCountChanged() will call GetRowCount()
   if (mTree) {
-    rv = mTree->RowCountChanged(row, -1);
-    NS_ENSURE_SUCCESS(rv,rv);
+    mTree->RowCountChanged(row, -1);
   }
 
   if (mAbViewListener && !mSuppressCountChange) {
@@ -172,7 +173,8 @@ NS_IMETHODIMP nsAbView::SetView(nsIAbDirectory *aAddressBook,
   {
     // Try and speed deletion of old cards by disconnecting the tree from us.
     mTreeSelection->ClearSelection();
-    mTree->SetView(nullptr);
+    IgnoredErrorResult rv2;
+    mTree->SetView(nullptr, mozilla::dom::CallerType::System, rv2);
   }
 
   // Clear out old cards
@@ -523,7 +525,7 @@ NS_IMETHODIMP nsAbView::GetCellText(int32_t row, nsTreeColumn* col, nsAString& _
   return GetCardValue(card, colID, _retval);
 }
 
-NS_IMETHODIMP nsAbView::SetTree(nsITreeBoxObject *tree)
+NS_IMETHODIMP nsAbView::SetTree(mozilla::dom::XULTreeElement *tree)
 {
   mTree = tree;
   return NS_OK;
@@ -545,9 +547,10 @@ nsresult nsAbView::InvalidateTree(int32_t row)
     return NS_OK;
 
   if (row == ALL_ROWS)
-    return mTree->Invalidate();
+    mTree->Invalidate();
   else
-    return mTree->InvalidateRow(row);
+    mTree->InvalidateRow(row);
+  return NS_OK;
 }
 
 NS_IMETHODIMP nsAbView::SelectionChangedXPCOM()
@@ -907,7 +910,7 @@ nsresult nsAbView::AddCard(AbCard *abcard, bool selectCardAfterAdding, int32_t *
 
   // This needs to happen after we insert the card, as RowCountChanged() will call GetRowCount()
   if (mTree)
-    rv = mTree->RowCountChanged(*index, 1);
+    mTree->RowCountChanged(*index, 1);
 
   // Checking for mTree here works around core bug 399227
   if (selectCardAfterAdding && mTreeSelection && mTree) {
@@ -1162,8 +1165,7 @@ nsresult nsAbView::ReselectCards(nsIArray *aCards, nsIAbCard *aIndexCard)
     NS_ENSURE_SUCCESS(rv, rv);
 
     if (mTree) {
-      rv = mTree->EnsureRowIsVisible(currentIndex);
-      NS_ENSURE_SUCCESS(rv, rv);
+      mTree->EnsureRowIsVisible(currentIndex);
     }
   }
 
diff --git a/mailnews/addrbook/src/nsAbView.h b/mailnews/addrbook/src/nsAbView.h
index 49c3519f46..f47d73bc3b 100644
--- a/mailnews/addrbook/src/nsAbView.h
+++ b/mailnews/addrbook/src/nsAbView.h
@@ -10,7 +10,7 @@
 #include "nsString.h"
 #include "nsIAbView.h"
 #include "nsITreeView.h"
-#include "nsITreeBoxObject.h"
+#include "mozilla/dom/XULTreeElement.h"
 #include "nsITreeSelection.h"
 #include "nsTArray.h"
 #include "nsIAbDirectory.h"
@@ -62,7 +62,7 @@ private:
   nsresult GetCardValue(nsIAbCard *card, const nsAString& colID, nsAString &_retval);
   nsresult RefreshTree();
 
-  nsCOMPtr<nsITreeBoxObject> mTree;
+  RefPtr<mozilla::dom::XULTreeElement> mTree;
   nsCOMPtr<nsITreeSelection> mTreeSelection;
   nsCOMPtr <nsIAbDirectory> mDirectory;
   nsTArray<AbCard*> mCards;
diff --git a/mailnews/base/src/nsMsgDBView.cpp b/mailnews/base/src/nsMsgDBView.cpp
index 77e6691c5c..f5de66524f 100644
--- a/mailnews/base/src/nsMsgDBView.cpp
+++ b/mailnews/base/src/nsMsgDBView.cpp
@@ -2334,7 +2334,7 @@ nsMsgDBView::CellTextForColumn(int32_t aRow,
 }
 
 NS_IMETHODIMP
-nsMsgDBView::SetTree(nsITreeBoxObject *tree)
+nsMsgDBView::SetTree(mozilla::dom::XULTreeElement *tree)
 {
   mTree = tree;
   return NS_OK;
@@ -3146,7 +3146,7 @@ nsMsgDBView::OperateOnMsgsInCollapsedThreads()
 {
   if (mTreeSelection)
   {
-    nsCOMPtr<nsITreeBoxObject> selTree;
+    RefPtr<mozilla::dom::XULTreeElement> selTree;
     mTreeSelection->GetTree(getter_AddRefs(selTree));
     // No tree means stand-alone message window.
     if (!selTree)
diff --git a/mailnews/base/src/nsMsgDBView.h b/mailnews/base/src/nsMsgDBView.h
index 698a588ca4..f103cc9009 100644
--- a/mailnews/base/src/nsMsgDBView.h
+++ b/mailnews/base/src/nsMsgDBView.h
@@ -14,7 +14,7 @@
 #include "MailNewsTypes.h"
 #include "nsIDBChangeListener.h"
 #include "nsITreeView.h"
-#include "nsITreeBoxObject.h"
+#include "mozilla/dom/XULTreeElement.h"
 #include "nsITreeSelection.h"
 #include "nsIMsgFolder.h"
 #include "nsIMsgThread.h"
@@ -134,7 +134,7 @@ protected:
   static char16_t* kForwardedString;
   static char16_t* kNewString;
 
-  nsCOMPtr<nsITreeBoxObject> mTree;
+  RefPtr<mozilla::dom::XULTreeElement> mTree;
   nsCOMPtr<nsITreeSelection> mTreeSelection;
   // We cache this to determine when to push command status notifications.
   uint32_t mNumSelectedRows;
diff --git a/mailnews/base/src/nsSubscribableServer.cpp b/mailnews/base/src/nsSubscribableServer.cpp
index 0049cb4ce5..7642882f92 100644
--- a/mailnews/base/src/nsSubscribableServer.cpp
+++ b/mailnews/base/src/nsSubscribableServer.cpp
@@ -716,7 +716,7 @@ nsSubscribableServer::GetRowCount(int32_t *rowCount)
 }
 
 NS_IMETHODIMP
-nsSubscribableServer::SetTree(nsITreeBoxObject *aTree)
+nsSubscribableServer::SetTree(mozilla::dom::XULTreeElement *aTree)
 {
   mTree = aTree;
   return NS_OK;
diff --git a/mailnews/base/src/nsSubscribableServer.h b/mailnews/base/src/nsSubscribableServer.h
index b0651fa4a8..4bbb99344e 100644
--- a/mailnews/base/src/nsSubscribableServer.h
+++ b/mailnews/base/src/nsSubscribableServer.h
@@ -9,7 +9,7 @@
 #include "nsCOMPtr.h"
 #include "nsString.h"
 #include "nsIMsgIncomingServer.h"
-#include "nsITreeBoxObject.h"
+#include "mozilla/dom/XULTreeElement.h"
 #include "nsITreeSelection.h"
 #include "nsITreeView.h"
 #include "nsISubscribableServer.h"
@@ -67,7 +67,7 @@ private:
   SubscribeTreeNode *mTreeRoot;          // root of the folder tree while items are discovered on the server
   nsTArray<SubscribeTreeNode*> mRowMap;  // array of nodes representing the rows for the tree element
   nsCOMPtr<nsITreeSelection> mSelection;
-  nsCOMPtr<nsITreeBoxObject> mTree;
+  RefPtr<mozilla::dom::XULTreeElement> mTree;
   nsresult FreeSubtree(SubscribeTreeNode *node);
   nsresult FreeRows();
   nsresult CreateNode(SubscribeTreeNode *parent, const char *name, const nsACString &aPath, SubscribeTreeNode **result);
diff --git a/mailnews/news/src/nsNntpIncomingServer.cpp b/mailnews/news/src/nsNntpIncomingServer.cpp
index 9d3719395b..df54951f30 100644
--- a/mailnews/news/src/nsNntpIncomingServer.cpp
+++ b/mailnews/news/src/nsNntpIncomingServer.cpp
@@ -31,7 +31,7 @@
 #include "mozilla/Services.h"
 #include "mozilla/dom/Element.h"
 #include "mozilla/ErrorResult.h"
-#include "nsITreeBoxObject.h"
+#include "mozilla/dom/XULTreeElement.h"
 #include "mozilla/dom/DataTransfer.h"
 
 #define INVALID_VERSION         0
@@ -1869,14 +1869,13 @@ nsNntpIncomingServer::GetCellText(int32_t row, nsTreeColumn* col, nsAString& _re
 }
 
 NS_IMETHODIMP
-nsNntpIncomingServer::SetTree(nsITreeBoxObject *tree)
+nsNntpIncomingServer::SetTree(mozilla::dom::XULTreeElement *tree)
 {
   mTree = tree;
   if (!tree)
     return NS_OK;
 
-  RefPtr<nsTreeColumns> cols;
-  tree->GetColumns(getter_AddRefs(cols));
+  RefPtr<nsTreeColumns> cols = tree->GetColumns();
   if (!cols)
     return NS_OK;
 
diff --git a/mailnews/news/src/nsNntpIncomingServer.h b/mailnews/news/src/nsNntpIncomingServer.h
index d825091b88..bd7357d1a4 100644
--- a/mailnews/news/src/nsNntpIncomingServer.h
+++ b/mailnews/news/src/nsNntpIncomingServer.h
@@ -104,7 +104,7 @@ private:
     // in the search view
     nsTArray<nsCString> mTempSubscribed;
 
-    nsCOMPtr<nsITreeBoxObject> mTree;
+    RefPtr<mozilla::dom::XULTreeElement> mTree;
     nsCOMPtr<nsITreeSelection> mTreeSelection;
 
     bool     mHasSeenBeginGroups;