[pygtk] Adding progressbar into a liststore

[Timo]

Hello, I want to make some sort of downloadmanager like Firefox has, but 
not that advanced. Just a window that adds a progressbar (and maybe a 
label) for each download. But I already get stuck by adding a 
progressbar into the liststore.
This is what I have:

        liststore  = gtk.ListStore(object)
        renderer = gtk.CellRendererText()
        column   = gtk.TreeViewColumn("Downloads",renderer, text=0)
        treeview.set_model(self.liststore)
        treeview.append_column(column)

        liststore.append([gtk.ProgressBar])

Then I get this error:

    Warning: unable to set property `text' of type `gchararray' from 
value of type `PyObject'

There is a row in the treeview, cause I can select one line, but nothing 
is in it.


Timo