commit ea748772ee7fd99d70a1ce119bc377c3e2083954
Author: Cody Russell <cody@jhu.edu>
Date:   Tue Jan 13 16:46:03 2015 -0600

    [GtkNSView] Add support for forwarding Cmd-Z to an NSTextView's undo manager

diff --git a/gtk/gtknsview.c b/gtk/gtknsview.c
index d5f8c76..9ba080d 100644
--- a/gtk/gtknsview.c
+++ b/gtk/gtknsview.c
@@ -712,6 +712,11 @@ gtk_ns_view_key_press (GtkWidget   *widget,

           switch (event->keyval)
             {
+            case GDK_KEY_z: /* undo */
+              if ([[text_view undoManager] canUndo])
+                [[text_view undoManager] undo];
+              return TRUE;
+
             case GDK_KEY_c: /* copy */
               if (has_selection)
                 [text_view copy: text_view];