PyGTK 2: TreeView is extending out of my window even with scroll bar enabled

Question

I have a Gtk window design as follows,

-Window
  |- Scroll_Window
    |- TreeView

With this design I am able to see tree view inside a scroll window with vertical scroll bar enabled. But the problem is, tree-view is extending out of my window. So if if do down the tree-view using arrow key, the tree-view cursor is going out of view (ie. Going down the actual scroll window).

But if I use my mouse to scroll the tree-view, I am able to see my tree-view data properly.

Expected behavior is on-arrow-down key press, tree-view should scroll by itself with cursor always visible.

Code:

import sys;
import dbf, gtk, pygtk, gobject;
pygtk.require('2.0');


w = gtk.Window(gtk.WINDOW_TOPLEVEL);
w.set_title("TEST");
sw = gtk.ScrolledWindow();
sw.set_border_width(10);
sw.set_policy(gtk.POLICY_AUTOMATIC, gtk.POLICY_AUTOMATIC);

treeView = gtk.TreeView();
listView = gtk.ListStore(gobject.TYPE_STRING, gobject.TYPE_STRING);

inData = [["a","1"],["b","bb"],["c","cc"],["d","dd"],["e","ee"],["f","ff"],["g","gg"],["h","hh"],["i","ii"],["j","jj"],["k","kk"],["l","ll"],["n","nn"]];
for nameTinList in inData:
  listIter = listView.append();
  listView.set_value(listIter, 0, nameTinList[0]);
  listView.set_value(listIter, 1, nameTinList[1]);

column = gtk.TreeViewColumn("Name", gtk.CellRendererText(), text=0);
column.set_resizable(False);
treeView.append_column(column);
column = gtk.TreeViewColumn("DESC", gtk.CellRendererText(), text=1);
column.set_resizable(False);
treeView.append_column(column);

treeView.set_model(listView);
sw.add_with_viewport(treeView);
w.add(sw);
w.show_all();

gtk.main();
w.destroy();

Output:

Answer 1

Replace sw.add_with_viewport(treeView) with sw.add(treeView), and scrolling with keyboard will work correctly.

As the documentation states, add_with_viewport is for child widgets without native scrolling capabilities. For widgets that implement scrolling, such as gtk.TextView or gtk.TreeView, the add method (inherited from gtk.Container) should be used.