add getItem and getItemIndex for List.

README.md

@@ -562,7 +562,7 @@ A scrollable list which can display selectable items.
 - inherits all from Box.
 - **add/addItem(text)** - add an item based on a string.
 - **removeItem(child)** - removes an item from the list. child can be an
-  element or an index.
+  element, index, or string.
 - **clearItems()** - clears all items from the list.
 - **setItems(items)** - sets the list items to multiple strings.
 - **select(index)** - select an index of an item.

lib/widget.js

@@ -4209,11 +4209,22 @@ List.prototype.appendItem = function(item) {
   }
 };
 
-List.prototype.removeItem = function(child) {
-  var i = typeof child !== 'number'
-    ? this.items.indexOf(child)
-    : child;
+List.prototype.getItemIndex = function(child) {
+  if (typeof child === 'number') {
+    return child;
+  } else if (typeof child === 'string') {
+    return this.ritems.indexOf(child);
+  } else {
+    return this.items.indexOf(child);
+  }
+};
 
+List.prototype.getItem = function(child) {
+  return this.items[this.getItemIndex(child)];
+};
+
+List.prototype.removeItem = function(child) {
+  var i = this.getItemIndex(child);
   if (~i && this.items[i]) {
     child = this.items.splice(i, 1)[0];
     this.ritems.splice(i, 1);