# display outside of this non-main thread
        uikit.do(self.display_categories)


    # insert content into gtk category list
    def display_categories(self):
        log.UI(self.module+".display_categories()", "mk tree, expand_all, select first path, currentcat")
    
        # rebuild gtk.TreeView
        log.UI("display_categoris: tree→gtk_cat")
        uikit.tree(self.gtk_cat, self.categories, title="Category", icon=gtk.STOCK_OPEN)

        # if it's a short list of categories, there's probably subfolders
        log.UI("display_categoris: expand_all")
        if len(self.categories) < 20:
            self.gtk_cat.expand_all()
            
        # select any first element
        self.gtk_cat.get_selection().select_path("0") #set_cursor
        self.currentcat()