# Notebook tab has been clicked (receives numeric page_num), but *NOT* yet changed (visually).
    def channel_switch(self, notebook, page, page_num=0, *args):
        self.current_channel = notebook.get_menu_label_text(notebook.get_nth_page(page_num))
        __print__(dbg.UI, "main.channel_switch() :=", self.current_channel)
        self.update_title()
        # if first selected, load current category
        # (run in thread, to make it look speedy on first startup)
        self.channel().first_show()
        self.thread( self.channel().first_show )

    # Invoked from the menu instead, uses module name instead of numeric tab id
    def channel_switch_by_name(self, name):
        self.notebook_channels.set_current_page(self.channel_names.index(name))

    # Mirror selected channel tab into main window title
    def update_title(self):