diff --git a/java/res/values/attrs.xml b/java/res/values/attrs.xml
index 3bd6619..c63ecbe 100644
--- a/java/res/values/attrs.xml
+++ b/java/res/values/attrs.xml
@@ -83,7 +83,12 @@
         <!-- Default width of a key, in pixels or percentage of display width. -->
         <attr name="keyWidth" format="dimension|fraction" />
         <!-- Default height of a row (key height + vertical gap), in pixels or percentage of
-             keyboard height. -->
+             keyboard height.
+             If the value is zero, the actual key width will be determined to fill out the area up
+             to the right edge of the keyboard.
+             If the value is negative, the actual key width will be determined to fill out the
+             area between the nearest key on the left hand side and the right edge of the keyboard.
+             -->
         <attr name="rowHeight" format="dimension|fraction" />
         <!-- Default horizontal gap between keys. -->
         <attr name="horizontalGap" format="dimension|fraction" />
@@ -142,6 +147,9 @@
         <attr name="shiftedIcon" format="reference" />
         <!-- The key is enabled and responds on press. -->
         <attr name="enabled" format="boolean" />
+        <!-- The X-coordinate of upper right corner of this key including horizontal gap.
+             If the value is negative, the origin is the right edge of the keyboard. -->
+        <attr name="keyXPos" format="dimension|fraction" />
     </declare-styleable>
 
     <declare-styleable name="Keyboard_Row">