column title button signals not working

[osa1]

I made this change in treeview example in the repo:

diff --git a/examples/treeview/src/treeview.rs b/examples/treeview/src/treeview.rs
index 39bd14f..3be128a 100644
--- a/examples/treeview/src/treeview.rs
+++ b/examples/treeview/src/treeview.rs
@@ -11,7 +11,11 @@ use rgtk::*;
 use rgtk::gtk::signals;

 fn append_text_column(tree: &mut gtk::TreeView) {
-    let column = gtk::TreeViewColumn::new().unwrap();
+    let mut column = gtk::TreeViewColumn::new().unwrap();
+    column.set_title("title");
+    column.set_clickable(true);
+    let column_btn: gtk::Button = column.get_button();
+    column_btn.connect(signals::Clicked::new(|| { println!("clicked"); }));
     let cell = gtk::CellRendererText::new().unwrap();
     column.pack_start(&cell, true);
     column.add_attribute(&cell, "text", 0);
@@ -37,7 +41,6 @@ fn main() {
     let left_store = gtk::ListStore::new(column_types).unwrap();
     let left_model = left_store.get_model().unwrap();
     left_tree.set_model(&left_model);
-    left_tree.set_headers_visible(false);
     append_text_column(&mut left_tree);

     for _ in range(0i, 10i) {
@@ -53,7 +56,6 @@ fn main() {
     let right_store = gtk::TreeStore::new(column_types).unwrap();
     let right_model = right_store.get_model().unwrap();
     right_tree.set_model(&right_model);
-    right_tree.set_headers_visible(false);
     append_text_column(&mut right_tree);

     for _ in range(0i, 10i) {

This puts headers to lists and makes them clickable. The problem is handlers are not working. It's not printing anything when I click to headers.

I'm not sure if relevant but GTK/GLib prints those to stdout when I run this program:

➜  treeview git:(master) ✗ cargo run
   Compiling rgtk-examples v0.0.1 (file:///home/omer/rust/rgtk/examples/treeview)
     Running `target/treeview`

(treeview:23066): GLib-GObject-CRITICAL **: g_object_ref: assertion 'G_IS_OBJECT (object)' failed

(treeview:23066): GLib-GObject-WARNING **: invalid (NULL) pointer instance

(treeview:23066): GLib-GObject-CRITICAL **: g_signal_connect_data: assertion 'G_TYPE_CHECK_INSTANCE (instance)' failed

(treeview:23066): GLib-GObject-CRITICAL **: g_object_unref: assertion 'G_IS_OBJECT (object)' failed

(treeview:23066): GLib-GObject-CRITICAL **: g_object_ref: assertion 'G_IS_OBJECT (object)' failed

(treeview:23066): GLib-GObject-WARNING **: invalid (NULL) pointer instance

(treeview:23066): GLib-GObject-CRITICAL **: g_signal_connect_data: assertion 'G_TYPE_CHECK_INSTANCE (instance)' failed

(treeview:23066): GLib-GObject-CRITICAL **: g_object_unref: assertion 'G_IS_OBJECT (object)' failed

[osa1]

This is because of #120 .