diff -r 000000000000 -r 6474c204b198 dom/webidl/TreeColumns.webidl
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/webidl/TreeColumns.webidl	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,57 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+interface MozTreeBoxObject;
+interface MozTreeColumn;
+
+[Func="IsChromeOrXBL"]
+interface TreeColumns {
+  /**
+   * The tree widget for these columns.
+   */
+  readonly attribute MozTreeBoxObject? tree;
+
+  /**
+   * The number of columns.
+   */
+  readonly attribute unsigned long count;
+
+  /**
+   * An alias for count (for the benefit of scripts which treat this as an
+   * array).
+   */
+  readonly attribute unsigned long length;
+
+  /**
+   * Get the first/last column.
+   */
+  MozTreeColumn? getFirstColumn();
+  MozTreeColumn? getLastColumn();
+
+  /**
+   * Attribute based column getters.
+   */
+  MozTreeColumn? getPrimaryColumn();
+  MozTreeColumn? getSortedColumn();
+  MozTreeColumn? getKeyColumn();
+
+  /**
+   * Get the column for the given element.
+   */
+  MozTreeColumn? getColumnFor(Element? element);
+
+  /**
+   * Parametric column getters.
+   */
+  getter MozTreeColumn? getNamedColumn(DOMString name);
+  getter MozTreeColumn? getColumnAt(unsigned long index);
+
+  /**
+   * This method is called whenever a treecol is added or removed and
+   * the column cache needs to be rebuilt.
+   */
+  void invalidateColumns();
+
+  void restoreNaturalOrder();
+};