diff --git a/modules/oojs-ui/OO.ui.js b/modules/oojs-ui/OO.ui.js
index 16332813a0..4bba1844e3 100644
--- a/modules/oojs-ui/OO.ui.js
+++ b/modules/oojs-ui/OO.ui.js
@@ -15,21 +15,78 @@ OO.ui = {};
 
 OO.ui.bind = $.proxy;
 
+/**
+ * Get the user's language and any fallback languages. These language codes are used by
+ * OO.ui.IconedElement to select localized icons in the user's language.
+ *
+ * In environments that provide a localization system, this function should be overridden to
+ * return the user's language(s). The default implementation returns English (en) only.
+ *
+ * @returns {string[]} Language codes, in descending order of priority
+ */
 OO.ui.getUserLanguages = function () {
 	return [ 'en' ];
 };
 
+( function () {
+
+/**
+ * Message store for the default implementation of OO.ui.msg
+ *
+ * Environments that provide a localization system should not use this, but should override
+ * OO.ui.msg altogether.
+ *
+ * @private
+ */
+var messages = {
+	// Label text for button to exit from dialog
+	'ooui-dialog-action-close': 'Close',
+	// TODO remove me
+	'ooui-inspector-close-tooltip': 'Close',
+	// TODO remove me
+	'ooui-inspector-remove-tooltip': 'Remove',
+	// Tool tip for a button that moves items in a list down one place
+	'ooui-outline-control-move-down': 'Move item down',
+	// Tool tip for a button that moves items in a list up one place
+	'ooui-outline-control-move-up': 'Move item up',
+	// Label for the toolbar group that contains a list of all other available tools
+	'ooui-toolbar-more': 'More'
+};
+
 /**
  * Get a localized message.
  *
+ * In environments that provide a localization system, this function should be overridden to
+ * return the message translated in the user's language. The default implementation always returns
+ * English messages.
+ *
+ * After the message key, message parameters may optionally be passed. In the default implementation,
+ * any occurrences of $1 are replaced with the first parameter, $2 with the second parameter, etc.
+ * Alternative implementations of OO.ui.msg may use any substitution system they like, as long as
+ * they support unnamed, ordered message parameters.
+ *
  * @abstract
  * @param {string} key Message key
  * @param {Mixed...} [params] Message parameters
+ * @returns {string} Translated message with parameters substituted
  */
 OO.ui.msg = function ( key ) {
-	return '[' + key + ']';
+	var message = messages[key], params = Array.prototype.slice.call( arguments, 1 );
+	if ( typeof message === 'string' ) {
+		// Perform $1 substitution
+		message = message.replace( /\$(\d+)/g, function ( unused, n ) {
+			var i = parseInt( n, 10 );
+			return params[i - 1] !== undefined ? params[i - 1] : '$' + n;
+		} );
+	} else {
+		// Return placeholder if message not found
+		message = '[' + key + ']';
+	}
+	return message;
 };
 
+} )();
+
 // Add more as you need
 OO.ui.Keys = {
 	'UNDEFINED': 0,
diff --git a/modules/oojs-ui/elements/OO.ui.IconedElement.js b/modules/oojs-ui/elements/OO.ui.IconedElement.js
index 321b037545..09612f00e8 100644
--- a/modules/oojs-ui/elements/OO.ui.IconedElement.js
+++ b/modules/oojs-ui/elements/OO.ui.IconedElement.js
@@ -14,7 +14,8 @@
  * @constructor
  * @param {jQuery} $icon Icon node, assigned to #$icon
  * @param {Object} [config] Configuration options
- * @cfg {Object|string} [icon=''] Symbolic icon name, or map of icon names keyed by language ID
+ * @cfg {Object|string} [icon=''] Symbolic icon name, or map of icon names keyed by language ID;
+ *  use the 'default' key to specify the icon to be used when there is no icon in the user's language.
  */
 OO.ui.IconedElement = function OoUiIconedElement( $icon, config ) {
 	// Config intialization
@@ -35,7 +36,7 @@ OO.ui.IconedElement = function OoUiIconedElement( $icon, config ) {
  * Set the icon.
  *
  * @method
- * @param {string} [value] Symbolic name of icon to use
+ * @param {Object|string} [value] Symbolic name of icon to use
  * @chainable
  */
 OO.ui.IconedElement.prototype.setIcon = function ( value ) {
diff --git a/modules/ve/init/ve.init.Platform.js b/modules/ve/init/ve.init.Platform.js
index 357218799e..f788e29c36 100644
--- a/modules/ve/init/ve.init.Platform.js
+++ b/modules/ve/init/ve.init.Platform.js
@@ -114,7 +114,7 @@ ve.init.Platform.prototype.getSystemPlatform = function () {
  * @returns {string[]} User language strings
  */
 ve.init.Platform.prototype.getUserLanguages = function () {
-	throw new Error( 've.init.Platform.getUserLanugages must be overridden in subclass' );
+	throw new Error( 've.init.Platform.getUserLanguages must be overridden in subclass' );
 };
 
 /**