diff --git a/system/selections.py b/system/selections.py
new file mode 100644
index 0000000..b52b930
--- /dev/null
+++ b/system/selections.py
@@ -0,0 +1,77 @@
+
+from system import logger, dataset
+
+import pygtk
+import gtk
+import gtk.gdk
+import gtk.glade
+import gnome
+import gnome.ui
+import gobject
+
+class SelectionTree(gtk.TreeView):
+    
+    def __init__(self):
+        self.store = gtk.TreeStore(gobject.TYPE_STRING)
+        gtk.TreeView.__init__(self, self.store)
+
+        renderer = gtk.CellRendererText()
+        sel_column = gtk.TreeViewColumn('Selection', renderer, text=0)
+        self.insert_column(sel_column, 0)
+
+        self.connect('row-activated', self.on_row_activated)
+
+        self._identifier_list = None
+        self._dim_list = {}
+
+        # A mapping of selection names to selection lines.
+        self._selections = {}
+
+        self.set_headers_visible(True)
+
+    def set_identifier_list(self, identifier_list):
+        self._identifier_list = identifier_list
+
+    def set_project(self, project):
+        self.project = project
+        project.add_selection_observer(self)
+        project.add_dataset_observer(self)
+        self.update_dims(project.dim_names)
+        
+    def selection_changed(self, selection):
+        self.update_dims(selection.keys())
+        
+    def dataset_changed(self):
+        self.selection_changed(self.project.get_selection())
+
+    def update_dims(self, dim_list):
+        for dim in dim_list:
+            if not self._dim_list.has_key(dim):
+                d = self.store.insert_after(None, None, (dim,))            
+                self._dim_list[dim] = d
+                self.store.insert_before(d, None, ('current selection',))
+
+    def on_row_activated(self, treeview, path, column):
+        i = self.store.get_iter(path)
+        p = self.store.iter_parent(i)
+        dim = self.store.get_value(p, 0)
+        id_list = self.project.get_selection()[dim]
+        self._identifier_list.set_identifiers(id_list)
+        
+
+class IdentifierList(gtk.TreeView):
+
+    def __init__(self):
+        self.store = gtk.ListStore(gobject.TYPE_STRING)
+        gtk.TreeView.__init__(self, self.store)
+
+        renderer = gtk.CellRendererText()
+        ids_column = gtk.TreeViewColumn('Identifiers', renderer, text=0)
+        self.insert_column(ids_column, 0)
+
+        self.set_headers_visible(True)
+
+    def set_identifiers(self, identifiers):
+        self.store.clear()
+        for e in identifiers:
+            self.store.append((e,))