Code:
	
def onButton_trigger(obj,state):
                	
	#judgement for x axis
	if obj == r_checkbox_x: 
		if state == viz.DOWN: 
			print "state=down"
								
		else: 
			print "state=up"
					
	#judgement for y axis
	if obj == r_checkbox_y: 
		if state == viz.DOWN: 
			print "state=down"
									
		else: 
			print "state=up"
			
	#judgement for z axis
	if obj == r_checkbox_z: 
		if state == viz.DOWN: 
			print "state=down"
									
		else: 
			print "state=up"
viz.callback(viz.BUTTON_EVENT, onButton_trigger)
 is that possible to set up some limit to guarantee that there is only one "obj" to be checked?
For example, when obj == r_checkbox_z    state is down, the states of obj == r_checkbox_x, obj == r_checkbox_y   are up.
The states of the three cannot be "up" at the same time.
Thanks,