diff --git a/java/res/values/attrs.xml b/java/res/values/attrs.xml
index 9358c90..3275cd0 100644
--- a/java/res/values/attrs.xml
+++ b/java/res/values/attrs.xml
@@ -194,8 +194,11 @@
         <attr name="moreKeys" format="string" />
         <!-- Maximum column of more keys keyboard -->
         <attr name="maxMoreKeysColumn" format="integer" />
-        <!-- Whether this is a functional key which has different key top than normal key. -->
-        <attr name="isFunctional" format="boolean" />
+        <attr name="backgroundType" format="enum">
+            <!-- This should be aligned with Key.BACKGROUND_TYPE_* -->
+            <enum name="normal" value="0" />
+            <enum name="functional" value="1" />
+        </attr>
         <!-- Whether this is a toggle key. -->
         <attr name="isSticky" format="boolean" />
         <!-- Whether long-pressing on this key will make it repeat. -->
diff --git a/java/res/xml-sw600dp/kbd_key_styles.xml b/java/res/xml-sw600dp/kbd_key_styles.xml
index 2c31e27..dfc7409 100644
--- a/java/res/xml-sw600dp/kbd_key_styles.xml
+++ b/java/res/xml-sw600dp/kbd_key_styles.xml
@@ -24,7 +24,7 @@
     <!-- Base key style for the functional key -->
     <key-style
         latin:styleName="functionalKeyStyle"
-        latin:isFunctional="true" />
+        latin:backgroundType="functional" />
     <!-- Base key style for the key which may have settings key as popup key -->
     <switch>
         <case
diff --git a/java/res/xml-sw768dp/kbd_key_styles.xml b/java/res/xml-sw768dp/kbd_key_styles.xml
index 6570ebc..f7dcc20 100644
--- a/java/res/xml-sw768dp/kbd_key_styles.xml
+++ b/java/res/xml-sw768dp/kbd_key_styles.xml
@@ -24,7 +24,7 @@
     <!-- Functional key styles -->
     <key-style
         latin:styleName="functionalKeyStyle"
-        latin:isFunctional="true" />
+        latin:backgroundType="functional" />
     <key-style
         latin:styleName="shiftKeyStyle"
         latin:code="@integer/key_shift"
diff --git a/java/res/xml/kbd_key_styles.xml b/java/res/xml/kbd_key_styles.xml
index 84b1900..e1f68d4 100644
--- a/java/res/xml/kbd_key_styles.xml
+++ b/java/res/xml/kbd_key_styles.xml
@@ -24,7 +24,7 @@
     <!-- Base key style for the functional key -->
     <key-style
         latin:styleName="functionalKeyStyle"
-        latin:isFunctional="true" />
+        latin:backgroundType="functional" />
     <!-- Base key style for the key which may have settings or tab key as popup key. -->
     <switch>
         <case
diff --git a/java/src/com/android/inputmethod/keyboard/Key.java b/java/src/com/android/inputmethod/keyboard/Key.java
index 06d248e..c4d5e85 100644
--- a/java/src/com/android/inputmethod/keyboard/Key.java
+++ b/java/src/com/android/inputmethod/keyboard/Key.java
@@ -102,8 +102,12 @@
      * {@link Keyboard#EDGE_TOP} and {@link Keyboard#EDGE_BOTTOM}.
      */
     private int mEdgeFlags;
-    /** Whether this is a functional key which has different key top than normal key */
-    public final boolean mFunctional;
+
+    /** Background type that represents different key background visual than normal one. */
+    public final int mBackgroundType;
+    public static final int BACKGROUND_TYPE_NORMAL = 0;
+    public static final int BACKGROUND_TYPE_FUNCTIONAL = 1;
+
     /** Whether this key repeats itself when held down */
     public final boolean mRepeatable;
 
@@ -225,7 +229,7 @@
         mEdgeFlags = edgeFlags;
         mHintLabel = hintLabel;
         mLabelOption = 0;
-        mFunctional = false;
+        mBackgroundType = BACKGROUND_TYPE_NORMAL;
         mSticky = false;
         mRepeatable = false;
         mMoreKeys = null;
@@ -325,8 +329,9 @@
         mMaxMoreKeysColumn = style.getInt(keyboardAttr, R.styleable.Keyboard_Key_maxMoreKeysColumn,
                 params.mMaxMiniKeyboardColumn);
 
+        mBackgroundType = style.getInt(
+                keyAttr, R.styleable.Keyboard_Key_backgroundType, BACKGROUND_TYPE_NORMAL);
         mRepeatable = style.getBoolean(keyAttr, R.styleable.Keyboard_Key_isRepeatable, false);
-        mFunctional = style.getBoolean(keyAttr, R.styleable.Keyboard_Key_isFunctional, false);
         mSticky = style.getBoolean(keyAttr, R.styleable.Keyboard_Key_isSticky, false);
         mEnabled = style.getBoolean(keyAttr, R.styleable.Keyboard_Key_enabled, true);
         mEdgeFlags = 0;
@@ -540,7 +545,7 @@
      */
     public int[] getCurrentDrawableState() {
         final boolean pressed = mPressed;
-        if (!mSticky && mFunctional) {
+        if (!mSticky && mBackgroundType == BACKGROUND_TYPE_FUNCTIONAL) {
             if (pressed) {
                 return KEY_STATE_FUNCTIONAL_PRESSED;
             } else {
diff --git a/java/src/com/android/inputmethod/keyboard/internal/KeyStyles.java b/java/src/com/android/inputmethod/keyboard/internal/KeyStyles.java
index 6d78e85..9800f24 100644
--- a/java/src/com/android/inputmethod/keyboard/internal/KeyStyles.java
+++ b/java/src/com/android/inputmethod/keyboard/internal/KeyStyles.java
@@ -172,7 +172,7 @@
             readInt(keyAttr, R.styleable.Keyboard_Key_keyIconPreview);
             readInt(keyAttr, R.styleable.Keyboard_Key_keyIconShifted);
             readInt(keyAttr, R.styleable.Keyboard_Key_maxMoreKeysColumn);
-            readBoolean(keyAttr, R.styleable.Keyboard_Key_isFunctional);
+            readInt(keyAttr, R.styleable.Keyboard_Key_backgroundType);
             readBoolean(keyAttr, R.styleable.Keyboard_Key_isSticky);
             readBoolean(keyAttr, R.styleable.Keyboard_Key_isRepeatable);
             readBoolean(keyAttr, R.styleable.Keyboard_Key_enabled);