diff --git a/dom/events/ContentEventHandler.cpp b/dom/events/ContentEventHandler.cpp
index 084743070a3..9ce70e6e151 100644
--- a/dom/events/ContentEventHandler.cpp
+++ b/dom/events/ContentEventHandler.cpp
@@ -203,13 +203,13 @@ ContentEventHandler::QueryContentRect(nsIContent* aContent,
 
   // get rect for first frame
   nsRect resultRect(nsPoint(0, 0), frame->GetRect().Size());
-  nsresult rv = ConvertToRootViewRelativeOffset(frame, resultRect);
+  nsresult rv = ConvertToRootRelativeOffset(frame, resultRect);
   NS_ENSURE_SUCCESS(rv, rv);
 
   // account for any additional frames
   while ((frame = frame->GetNextContinuation()) != nullptr) {
     nsRect frameRect(nsPoint(0, 0), frame->GetRect().Size());
-    rv = ConvertToRootViewRelativeOffset(frame, frameRect);
+    rv = ConvertToRootRelativeOffset(frame, frameRect);
     NS_ENSURE_SUCCESS(rv, rv);
     resultRect.UnionRect(resultRect, frameRect);
   }
@@ -1017,7 +1017,7 @@ ContentEventHandler::OnQueryTextRect(WidgetQueryContentEvent* aEvent)
 
   // get the starting frame rect
   nsRect rect(nsPoint(0, 0), firstFrame->GetRect().Size());
-  rv = ConvertToRootViewRelativeOffset(firstFrame, rect);
+  rv = ConvertToRootRelativeOffset(firstFrame, rect);
   NS_ENSURE_SUCCESS(rv, rv);
   nsRect frameRect = rect;
   nsPoint ptOffset;
@@ -1059,7 +1059,7 @@ ContentEventHandler::OnQueryTextRect(WidgetQueryContentEvent* aEvent)
       }
     }
     frameRect.SetRect(nsPoint(0, 0), frame->GetRect().Size());
-    rv = ConvertToRootViewRelativeOffset(frame, frameRect);
+    rv = ConvertToRootRelativeOffset(frame, frameRect);
     NS_ENSURE_SUCCESS(rv, rv);
     if (frame != lastFrame) {
       // not last frame, so just add rect to previous result
@@ -1125,7 +1125,7 @@ ContentEventHandler::OnQueryCaretRect(WidgetQueryContentEvent* aEvent)
                                     lineBreakType);
       NS_ENSURE_SUCCESS(rv, rv);
       if (offset == aEvent->mInput.mOffset) {
-        rv = ConvertToRootViewRelativeOffset(caretFrame, caretRect);
+        rv = ConvertToRootRelativeOffset(caretFrame, caretRect);
         NS_ENSURE_SUCCESS(rv, rv);
         nscoord appUnitsPerDevPixel =
           caretFrame->PresContext()->AppUnitsPerDevPixel();
@@ -1186,7 +1186,7 @@ ContentEventHandler::OnQueryCaretRect(WidgetQueryContentEvent* aEvent)
     rect.height = fontHeight;
   }
 
-  rv = ConvertToRootViewRelativeOffset(frame, rect);
+  rv = ConvertToRootRelativeOffset(frame, rect);
   NS_ENSURE_SUCCESS(rv, rv);
 
   aEvent->mReply.mRect = LayoutDevicePixel::FromUntyped(
@@ -1547,18 +1547,21 @@ ContentEventHandler::GetStartFrameAndOffset(const nsRange* aRange,
 }
 
 nsresult
-ContentEventHandler::ConvertToRootViewRelativeOffset(nsIFrame* aFrame,
-                                                     nsRect& aRect)
+ContentEventHandler::ConvertToRootRelativeOffset(nsIFrame* aFrame,
+                                                 nsRect& aRect)
 {
   NS_ASSERTION(aFrame, "aFrame must not be null");
 
-  nsView* view = nullptr;
-  nsPoint posInView;
-  aFrame->GetOffsetFromView(posInView, &view);
-  if (!view) {
+  nsPresContext* rootPresContext = aFrame->PresContext()->GetRootPresContext();
+  if (NS_WARN_IF(!rootPresContext)) {
     return NS_ERROR_FAILURE;
   }
-  aRect += posInView + view->GetOffsetTo(nullptr);
+  nsIFrame* rootFrame = rootPresContext->PresShell()->GetRootFrame();
+  if (NS_WARN_IF(!rootFrame)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  aRect = nsLayoutUtils::TransformFrameRectToAncestor(aFrame, aRect, rootFrame);
   return NS_OK;
 }
 
diff --git a/dom/events/ContentEventHandler.h b/dom/events/ContentEventHandler.h
index 2707789e4a9..80810a3b15a 100644
--- a/dom/events/ContentEventHandler.h
+++ b/dom/events/ContentEventHandler.h
@@ -136,9 +136,10 @@ protected:
   nsresult GetStartFrameAndOffset(const nsRange* aRange,
                                   nsIFrame*& aFrame,
                                   int32_t& aOffsetInFrame);
-  // Convert the frame relative offset to the root view relative offset.
-  nsresult ConvertToRootViewRelativeOffset(nsIFrame* aFrame,
-                                           nsRect& aRect);
+  // Convert the frame relative offset to the root frame of the root presContext
+  // relative offset.
+  nsresult ConvertToRootRelativeOffset(nsIFrame* aFrame,
+                                       nsRect& aRect);
   // Expand aXPOffset to the nearest offset in cluster boundary. aForward is
   // true, it is expanded to forward.
   nsresult ExpandToClusterBoundary(nsIContent* aContent, bool aForward,
diff --git a/widget/TextEvents.h b/widget/TextEvents.h
index 44dab1b6294..8f6e999f169 100644
--- a/widget/TextEvents.h
+++ b/widget/TextEvents.h
@@ -582,7 +582,11 @@ public:
     // This is the offset where caret would be if user clicked at the refPoint.
     uint32_t mTentativeCaretOffset;
     nsString mString;
-    // Finally, the coordinates is system coordinates.
+    // mRect is used by eQueryTextRect, eQueryCaretRect, eQueryCharacterAtPoint
+    // and eQueryEditorRect. The coordinates is system coordinates relative to
+    // the top level widget of mFocusedWidget.  E.g., if a <xul:panel> which
+    // is owned by a window has focused editor, the offset of mRect is relative
+    // to the owner window, not the <xul:panel>.
     mozilla::LayoutDeviceIntRect mRect;
     // The return widget has the caret. This is set at all query events.
     nsIWidget* mFocusedWidget;
diff --git a/widget/tests/window_composition_text_querycontent.xul b/widget/tests/window_composition_text_querycontent.xul
index cbe256bc0d7..2b61e8cfc58 100644
--- a/widget/tests/window_composition_text_querycontent.xul
+++ b/widget/tests/window_composition_text_querycontent.xul
@@ -2309,6 +2309,86 @@ function runCharAtPointAtOutsideTest()
   }
 }
 
+function runCSSTransformTest()
+{
+  textarea.focus();
+  textarea.value = "some text";
+  textarea.selectionStart = textarea.selectionEnd = textarea.value.length;
+  var editorRect = synthesizeQueryEditorRect();
+  if (!checkQueryContentResult(editorRect,
+        "runCSSTransformTest: editorRect")) {
+    return;
+  }
+  var firstCharRect = synthesizeQueryTextRect(0, 1);
+  if (!checkQueryContentResult(firstCharRect,
+        "runCSSTransformTest: firstCharRect")) {
+    return;
+  }
+  var lastCharRect = synthesizeQueryTextRect(textarea.value.length - 1, textarea.value.length);
+  if (!checkQueryContentResult(lastCharRect,
+        "runCSSTransformTest: lastCharRect")) {
+    return;
+  }
+  var caretRect = synthesizeQueryCaretRect(textarea.selectionStart);
+  if (!checkQueryContentResult(caretRect,
+        "runCSSTransformTest: caretRect")) {
+    return;
+  }
+  var caretRectBeforeFirstChar = synthesizeQueryCaretRect(0);
+  if (!checkQueryContentResult(caretRectBeforeFirstChar,
+        "runCSSTransformTest: caretRectBeforeFirstChar")) {
+    return;
+  }
+
+  try {
+    textarea.style.transform = "translate(10px, 15px)";
+    function movedRect(aRect, aX, aY)
+    {
+      return { left: aRect.left + aX, top: aRect.top + aY, width: aRect.width, height: aRect.height }
+    }
+
+    var editorRectTranslated = synthesizeQueryEditorRect();
+    if (!checkQueryContentResult(editorRectTranslated,
+          "runCSSTransformTest: editorRectTranslated") ||
+        !checkRect(editorRectTranslated, movedRect(editorRect, 10, 15),
+          "runCSSTransformTest: editorRectTranslated")) {
+      return;
+    }
+    var firstCharRectTranslated = synthesizeQueryTextRect(0, 1);
+    if (!checkQueryContentResult(firstCharRectTranslated,
+          "runCSSTransformTest: firstCharRectTranslated") ||
+        !checkRect(firstCharRectTranslated, movedRect(firstCharRect, 10, 15),
+          "runCSSTransformTest: firstCharRectTranslated")) {
+      return;
+    }
+    var lastCharRectTranslated = synthesizeQueryTextRect(textarea.value.length - 1, textarea.value.length);
+    if (!checkQueryContentResult(lastCharRectTranslated,
+          "runCSSTransformTest: lastCharRectTranslated") ||
+        !checkRect(lastCharRectTranslated, movedRect(lastCharRect, 10, 15),
+          "runCSSTransformTest: lastCharRectTranslated")) {
+      return;
+    }
+    var caretRectTranslated = synthesizeQueryCaretRect(textarea.selectionStart);
+    if (!checkQueryContentResult(caretRectTranslated,
+          "runCSSTransformTest: caretRectTranslated") ||
+        !checkRect(caretRectTranslated, movedRect(caretRect, 10, 15),
+          "runCSSTransformTest: caretRectTranslated")) {
+      return;
+    }
+    var caretRectBeforeFirstCharTranslated = synthesizeQueryCaretRect(0);
+    if (!checkQueryContentResult(caretRectBeforeFirstCharTranslated,
+          "runCSSTransformTest: caretRectBeforeFirstCharTranslated") ||
+        !checkRect(caretRectBeforeFirstCharTranslated, movedRect(caretRectBeforeFirstChar, 10, 15),
+          "runCSSTransformTest: caretRectBeforeFirstCharTranslated")) {
+      return;
+    }
+
+    // XXX It's too difficult to check the result with scale and rotate...
+  } finally {
+    textarea.style.transform = "";
+  }
+}
+
 function runBug722639Test()
 {
   textarea.focus();
@@ -4522,6 +4602,7 @@ function runTest()
   runCompositionEventTest();
   runCharAtPointTest(textarea, "textarea in the document");
   runCharAtPointAtOutsideTest();
+  runCSSTransformTest();
   runBug722639Test();
   runForceCommitTest();
   runNestedSettingValue();