Hi Jeff, thanks for your review. Some comments inline.

> This is quite interesting! A couple of things though:
> 
> - mousing over the "Add" submenu makes two menus appear (the toolbar's popup
> menu shows up). Wtf?
Fixed.
> - how do we actually edit the contents now? What's the difference in the glade
> editor?
We still edit the contents like before. We create in glade some more widgets (eg. TreeViewColumns and CellRenderers) and then we get these objects via GtkBuilder.

> - maybe you want to take a look at lp:~kiddo/specto/pygi too
Yeah, I've tried to start it but crashes. (pygi + Gtk+ 3.0)
> - I guess this simplifies the code a lot, however I'd like someone else to
> review this too
> - it looks different than the current UI... the patch below makes it ressemble
> the main branch more, but it still has different column headers, the
> checkboxes are not centered, etc.
Thanks for the patch. I've tried to align the checkboxes with no luck in glade, I wonder if it's a bug. I'll ping you again when this issue will be fixed.
> 
> 
> 
> === modified file 'data/uis/notifier.ui'
> --- data/uis/notifier.ui        2011-05-13 09:56:54 +0000
> +++ data/uis/notifier.ui        2011-05-15 22:15:31 +0000
> @@ -1,7 +1,6 @@
>  <?xml version="1.0" encoding="UTF-8"?>
>  <interface>
>    <requires lib="gtk+" version="2.18"/>
> -  <!-- interface-naming-policy toplevel-contextual -->
>    <object class="GtkAccelGroup" id="accelgroup1"/>
>    <object class="GtkWindow" id="error_dialog">
>      <property name="can_focus">False</property>
> @@ -57,8 +56,6 @@
>                <object class="GtkScrolledWindow" id="scrolledwindow1">
>                  <property name="visible">True</property>
>                  <property name="can_focus">True</property>
> -                <property name="hscrollbar_policy">automatic</property>
> -                <property name="vscrollbar_policy">automatic</property>
>                  <child>
>                    <object class="GtkTextView" id="error_message">
>                      <property name="height_request">200</property>
> @@ -612,18 +609,19 @@
>              <property name="visible">True</property>
>              <property name="can_focus">True</property>
>              <property name="hscrollbar_policy">never</property>
> -            <property name="vscrollbar_policy">automatic</property>
>              <property name="shadow_type">in</property>
>              <child>
>                <object class="GtkTreeView" id="treeview">
>                  <property name="visible">True</property>
>                  <property name="can_focus">True</property>
>                  <property name="model">liststore</property>
> -                <property name="headers_clickable">False</property>
> +                <property name="rules_hint">True</property>
>                  <property name="search_column">0</property>
> -                <property name="enable_grid_lines">both</property>
>                  <signal name="cursor-changed" handler="show_watch_info"
> swapped="no"/>
>                  <signal name="row-activated" handler="open_watch_callback"
> swapped="no"/>
> +                <child internal-child="selection">
> +                  <object class="GtkTreeSelection" id="treeview-selection1"/>
> +                </child>
>                  <child>
>                    <object class="GtkTreeViewColumn"
> id="select_treeviewcolumn">
>                      <property name="title"
> translatable="yes">Select</property>