# File test/unit/ui/util/observable.rb, line 76
     def notify_listeners(channel_name, value=NOTHING)
						channel = channels[channel_name]
						count = 0
						unless (channel.nil?)
							arguments = [value]
							arguments.delete(NOTHING)
							channel.each_value {
								|callback|
								callback.call(*arguments)
								count += 1
							}
						end
						return count
					end