--- a/dom/events/IMEContentObserver.cpp
+++ b/dom/events/IMEContentObserver.cpp
@@ -130,21 +130,23 @@ public:
              const IMENotification::TextChangeDataBase& aData)
   {
     if (!aData.IsValid()) {
       AppendLiteral("{ IsValid()=false }");
       return;
     }
     AppendPrintf("{ mStartOffset=%u, mRemovedEndOffset=%u, mAddedEndOffset=%u, "
                  "mCausedOnlyByComposition=%s, "
-                 "mIncludingChangesDuringComposition=%s }",
+                 "mIncludingChangesDuringComposition=%s, "
+                 "mIncludingChangesWithoutComposition=%s }",
                  aData.mStartOffset, aData.mRemovedEndOffset,
                  aData.mAddedEndOffset,
                  ToChar(aData.mCausedOnlyByComposition),
-                 ToChar(aData.mIncludingChangesDuringComposition));
+                 ToChar(aData.mIncludingChangesDuringComposition),
+                 ToChar(aData.mIncludingChangesWithoutComposition));
   }
   virtual ~TextChangeDataToString() {}
 };
 
 /******************************************************************************
  * mozilla::IMEContentObserver
  ******************************************************************************/
 

--- a/widget/IMEData.h
+++ b/widget/IMEData.h
@@ -731,16 +731,19 @@ struct IMENotification final
     // mCausedOnlyByComposition is true only when *all* merged changes are
     // caused by composition.
     bool mCausedOnlyByComposition;
     // mIncludingChangesDuringComposition is true if at least one change which
     // is not caused by composition occurred during the last composition.
     // Note that if after the last composition is finished and there are some
     // changes not caused by composition, this is set to false.
     bool mIncludingChangesDuringComposition;
+    // mIncludingChangesWithoutComposition is true if there is at least one
+    // change which did occur when there wasn't a composition ongoing.
+    bool mIncludingChangesWithoutComposition;
 
     uint32_t OldLength() const
     {
       MOZ_ASSERT(IsValid());
       return mRemovedEndOffset - mStartOffset;
     }
     uint32_t NewLength() const
     {
@@ -804,16 +807,18 @@ struct IMENotification final
       MOZ_ASSERT(aAddedEndOffset >= aStartOffset,
                  "added end offset must not be smaller than start offset");
       mStartOffset = aStartOffset;
       mRemovedEndOffset = aRemovedEndOffset;
       mAddedEndOffset = aAddedEndOffset;
       mCausedOnlyByComposition = aCausedByComposition;
       mIncludingChangesDuringComposition =
         !aCausedByComposition && aOccurredDuringComposition;
+      mIncludingChangesWithoutComposition =
+        !aCausedByComposition && !aOccurredDuringComposition;
     }
   };
 
   struct MouseButtonEventData
   {
     // The value of WidgetEvent::mMessage
     EventMessage mEventMessage;
     // Character offset from the start of the focused editor under the cursor

--- a/widget/nsBaseWidget.cpp
+++ b/widget/nsBaseWidget.cpp
@@ -2164,21 +2164,29 @@ IMENotification::TextChangeDataBase::Mer
 
   const TextChangeDataBase& newData = aOther;
   const TextChangeDataBase oldData = *this;
 
   // mCausedOnlyByComposition should be true only when all changes are caused
   // by composition.
   mCausedOnlyByComposition =
     newData.mCausedOnlyByComposition && oldData.mCausedOnlyByComposition;
+
+  // mIncludingChangesWithoutComposition should be true if at least one of
+  // merged changes occurred without composition.
+  mIncludingChangesWithoutComposition =
+    newData.mIncludingChangesWithoutComposition ||
+      oldData.mIncludingChangesWithoutComposition;
+
   // mIncludingChangesDuringComposition should be true when at least one of
   // the merged non-composition changes occurred during the latest composition.
-
   if (!newData.mCausedOnlyByComposition &&
       !newData.mIncludingChangesDuringComposition) {
+    MOZ_ASSERT(newData.mIncludingChangesWithoutComposition);
+    MOZ_ASSERT(mIncludingChangesWithoutComposition);
     // If new change is neither caused by composition nor occurred during
     // composition, set mIncludingChangesDuringComposition to false because
     // IME doesn't want outdated text changes as text change during current
     // composition.
     mIncludingChangesDuringComposition = false;
   } else {
     // Otherwise, set mIncludingChangesDuringComposition to true if either
     // oldData or newData includes changes during composition.

--- a/widget/nsGUIEventIPC.h
+++ b/widget/nsGUIEventIPC.h
@@ -782,25 +782,29 @@ struct ParamTraits<mozilla::widget::IMEN
 
   static void Write(Message* aMsg, const paramType& aParam)
   {
     WriteParam(aMsg, aParam.mStartOffset);
     WriteParam(aMsg, aParam.mRemovedEndOffset);
     WriteParam(aMsg, aParam.mAddedEndOffset);
     WriteParam(aMsg, aParam.mCausedOnlyByComposition);
     WriteParam(aMsg, aParam.mIncludingChangesDuringComposition);
+    WriteParam(aMsg, aParam.mIncludingChangesWithoutComposition);
   }
 
   static bool Read(const Message* aMsg, void** aIter, paramType* aResult)
   {
     return ReadParam(aMsg, aIter, &aResult->mStartOffset) &&
            ReadParam(aMsg, aIter, &aResult->mRemovedEndOffset) &&
            ReadParam(aMsg, aIter, &aResult->mAddedEndOffset) &&
            ReadParam(aMsg, aIter, &aResult->mCausedOnlyByComposition) &&
-           ReadParam(aMsg, aIter, &aResult->mIncludingChangesDuringComposition);
+           ReadParam(aMsg, aIter,
+                     &aResult->mIncludingChangesDuringComposition) &&
+           ReadParam(aMsg, aIter,
+                     &aResult->mIncludingChangesWithoutComposition);
   }
 };
 
 template<>
 struct ParamTraits<mozilla::widget::IMENotification::MouseButtonEventData>
 {
   typedef mozilla::widget::IMENotification::MouseButtonEventData paramType;
 

--- a/widget/windows/TSFTextStore.cpp
+++ b/widget/windows/TSFTextStore.cpp
@@ -4601,24 +4601,26 @@ TSFTextStore::OnTextChangeInternal(const
   const IMENotification::TextChangeDataBase& textChangeData =
     aIMENotification.mTextChangeData;
 
   MOZ_LOG(sTextStoreLog, LogLevel::Debug,
          ("TSF: 0x%p   TSFTextStore::OnTextChangeInternal(aIMENotification={ "
           "mMessage=0x%08X, mTextChangeData={ mStartOffset=%lu, "
           "mRemovedEndOffset=%lu, mAddedEndOffset=%lu, "
           "mCausedOnlyByComposition=%s, "
-          "mIncludingChangesDuringComposition=%s }), "
+          "mIncludingChangesDuringComposition=%s, "
+          "mIncludingChangesWithoutComposition=%s }), "
           "mSink=0x%p, mSinkMask=%s, mComposition.IsComposing()=%s",
           this, aIMENotification.mMessage,
           textChangeData.mStartOffset,
           textChangeData.mRemovedEndOffset,
           textChangeData.mAddedEndOffset,
           GetBoolName(textChangeData.mCausedOnlyByComposition),
           GetBoolName(textChangeData.mIncludingChangesDuringComposition),
+          GetBoolName(textChangeData.mIncludingChangesWithoutComposition),
           mSink.get(),
           GetSinkMaskNameStr(mSinkMask).get(),
           GetBoolName(mComposition.IsComposing())));
 
   if (textChangeData.mCausedOnlyByComposition) {
     // Ignore text change notifications caused only by composition since it's
     // already been handled internally.
     return NS_OK;