diff --git a/widget/cocoa/TextInputHandler.h b/widget/cocoa/TextInputHandler.h
index ce661d6e8f4..cf834b40a23 100644
--- a/widget/cocoa/TextInputHandler.h
+++ b/widget/cocoa/TextInputHandler.h
@@ -175,18 +175,14 @@ public:
   void InitByInputSourceID(const CFStringRef aID);
   /**
    * InitByLayoutID() initializes the keyboard layout by the layout ID.
-   * The KeyboardLayoutIdentifier (SInt32), used by Apple's now-deprecated
-   * Keyboard Layout Services, is no longer used by its replacement --
-   * Apple's Text Input Services (TIS).  All the layout IDs currently
-   * supported by InitByLayoutID() are backwards-compatible with the layout
-   * IDs used by Keyboard Layout Services.  But there's no need to contine
-   * maintaining backwards compatibility as support for new IDs is added.
    *
    * @param aLayoutID             An ID of keyboard layout.
-   *                                     0: US
-   *                                -18944: Greek
-   *                                     3: German
-   *                                   224: Swedish-Pro
+   *                                0: US
+   *                                1: Greek
+   *                                2: German
+   *                                3: Swedish-Pro
+   *                                4: Dvorak-Qwerty Cmd
+   *                                5: Thai
    * @param aOverrideKeyboard     When testing set to TRUE, otherwise, set to
    *                              FALSE.  When TRUE, we use an ANSI keyboard
    *                              instead of the actual keyboard.
diff --git a/widget/cocoa/TextInputHandler.mm b/widget/cocoa/TextInputHandler.mm
index 862f9e7cb6d..2479abc60b8 100644
--- a/widget/cocoa/TextInputHandler.mm
+++ b/widget/cocoa/TextInputHandler.mm
@@ -448,15 +448,21 @@ TISInputSourceWrapper::InitByLayoutID(SInt32 aLayoutID,
     case 0:
       InitByInputSourceID("com.apple.keylayout.US");
       break;
-    case -18944:
+    case 1:
       InitByInputSourceID("com.apple.keylayout.Greek");
       break;
-    case 3:
+    case 2:
       InitByInputSourceID("com.apple.keylayout.German");
       break;
-    case 224:
+    case 3:
       InitByInputSourceID("com.apple.keylayout.Swedish-Pro");
       break;
+    case 4:
+      InitByInputSourceID("com.apple.keylayout.DVORAK-QWERTYCMD");
+      break;
+    case 5:
+      InitByInputSourceID("com.apple.keylayout.Thai");
+      break;
     default:
       Clear();
       break;
@@ -876,8 +882,12 @@ TISInputSourceWrapper::InitKeyPressEvent(NSEvent *aNativeKeyEvent,
 
   // If the current keyboard layout is switched by the Cmd key,
   // we should append cmdedChar and shiftedCmdChar that are
-  // Latin char for the key. But don't append at Dvorak-QWERTY.
-  if ((cmdedChar || cmdedShiftChar) && isCmdSwitchLayout && !isDvorakQWERTY) {
+  // Latin char for the key.
+  // If the keyboard layout is Dvorak-QWERTY, we should append them only when
+  // command key is pressed because when command key isn't pressed, uncmded
+  // chars have been appended already.
+  if ((cmdedChar || cmdedShiftChar) && isCmdSwitchLayout &&
+      (aKeyEvent.isMeta || !isDvorakQWERTY)) {
     nsAlternativeCharCode altCharCodes(cmdedChar, cmdedShiftChar);
     aKeyEvent.alternativeCharCodes.AppendElement(altCharCodes);
   }
diff --git a/widget/tests/test_keycodes.xul b/widget/tests/test_keycodes.xul
index aac21a41aa3..b727a3f44a8 100644
--- a/widget/tests/test_keycodes.xul
+++ b/widget/tests/test_keycodes.xul
@@ -73,15 +73,16 @@ function synthesizeNativeKey(aLayout, aKeyCode, aModifiers, aSystemChars,
 
 var keyboardLayouts;
 if (IS_MAC) {
-  // These constants can be found by inspecting files under
-  // /System/Library/Keyboard\ Layouts/Unicode.bundle/Contents/Resources/
-  // XXX if you need a new keyboard layout and that uses KCHR resource,
-  // you need to modify GetScriptFromKeyboardLayout of nsChildView.mm
+  // Any unused number is okay for adding new keyboard layout.
+  // When you add new keyboard layout here, you need to modify
+  // TISInputSourceWrapper::InitByLayoutID().
   keyboardLayouts = {
-    "US":0,
-    "Greek":-18944,
-    "German":3,
-    "Swedish":224
+    "US":              0,
+    "Greek":           1,
+    "German":          2,
+    "Swedish":         3,
+    "Dvorak-Qwerty":   4,
+    "Thai":            5
   };
 } else if (IS_WIN) {
   // These constants can be found by inspecting registry keys under
@@ -403,6 +404,11 @@ function runKeyEventTests()
             "", SHOULD_DELIVER_KEYDOWN);
     testKey({layout:"US", keyCode:54, commandRight:0, chars:"", unmodifiedChars:""},
             "", SHOULD_DELIVER_KEYUP);
+
+   testKey({layout:"Dvorak-Qwerty", keyCode:0x22, command:1, alt:1, chars:"^", unmodifiedChars:"c"},
+           "^", SHOULD_DELIVER_KEYDOWN_KEYPRESS);
+   testKey({layout:"Dvorak-Qwerty", keyCode:0x22, command:1, alt:1, shift:1, chars:"\u02C6", unmodifiedChars:"C"},
+           "\u02C6", SHOULD_DELIVER_KEYDOWN_KEYPRESS);
   }
   else if (IS_WIN) {
     // On Windows, you can use Spy++ or Winspector (free) to watch window messages.