diff --git a/dom/browser-element/BrowserElementCopyPaste.js b/dom/browser-element/BrowserElementCopyPaste.js
index ae5a8f091bf..919179a7a60 100644
--- a/dom/browser-element/BrowserElementCopyPaste.js
+++ b/dom/browser-element/BrowserElementCopyPaste.js
@@ -71,7 +71,8 @@ let CopyPasteAssistent = {
       reason: e.reason,
       collapsed: e.collapsed,
       caretVisible: e.caretVisible,
-      selectionVisible: e.selectionVisible
+      selectionVisible: e.selectionVisible,
+      selectionEditable: e.selectionEditable
     };
 
     // Get correct geometry information if we have nested iframe.
diff --git a/dom/browser-element/BrowserElementParent.js b/dom/browser-element/BrowserElementParent.js
index b563a95ce92..ee1ecd1e7b4 100644
--- a/dom/browser-element/BrowserElementParent.js
+++ b/dom/browser-element/BrowserElementParent.js
@@ -452,6 +452,7 @@ BrowserElementParent.prototype = {
   //  - collapsed: Indicate current selection is collapsed or not.
   //  - caretVisible: Indicate the caret visiibility.
   //  - selectionVisible: Indicate current selection is visible or not.
+  //  - selectionEditable: Indicate current selection is editable or not.
   _handleCaretStateChanged: function(data) {
     let evt = this._createEvent('caretstatechanged', data.json,
                                 /* cancelable = */ false);
diff --git a/dom/webidl/CaretStateChangedEvent.webidl b/dom/webidl/CaretStateChangedEvent.webidl
index 45a4e38d301..d016513ca0e 100644
--- a/dom/webidl/CaretStateChangedEvent.webidl
+++ b/dom/webidl/CaretStateChangedEvent.webidl
@@ -19,6 +19,7 @@ dictionary CaretStateChangedEventInit : EventInit {
   CaretChangedReason reason = "visibilitychange";
   boolean caretVisible = false;
   boolean selectionVisible = false;
+  boolean selectionEditable = false;
 };
 
 [Constructor(DOMString type, optional CaretStateChangedEventInit eventInit),
@@ -29,4 +30,5 @@ interface CaretStateChangedEvent : Event {
   readonly attribute CaretChangedReason reason;
   readonly attribute boolean caretVisible;
   readonly attribute boolean selectionVisible;
+  readonly attribute boolean selectionEditable;
 };
diff --git a/layout/base/AccessibleCaretManager.cpp b/layout/base/AccessibleCaretManager.cpp
index ce286e59088..edd2b6a5ba7 100644
--- a/layout/base/AccessibleCaretManager.cpp
+++ b/layout/base/AccessibleCaretManager.cpp
@@ -941,6 +941,11 @@ AccessibleCaretManager::DispatchCaretStateChangedEvent(CaretChangedReason aReaso
     init.mSelectionVisible = true;
   }
 
+  // Send isEditable info w/ event detail. This info can help determine
+  // whether to show cut command on selection dialog or not.
+  init.mSelectionEditable = commonAncestorFrame &&
+    commonAncestorFrame->GetContent()->GetEditingHost();
+
   init.mBoundingClientRect = domRect;
   init.mReason = aReason;
   init.mCollapsed = sel->IsCollapsed();