var speed = 50;        
var max_opacity = 100;  
var min_opacity = 40; 
var do_step  =  15;      



 function change_opacity(obj,do_option)
 {
  if(obj.doing)
   clearInterval(obj.doing);
  obj.doing = setInterval(do_option+"_alpha("+obj.sourceIndex+")",speed); 
 }
 

 function down_alpha(obj_index)
 {
  var obj = document.all[obj_index];
  
  if(obj.filters.Alpha.Opacity > min_opacity )
  {
   obj.filters.Alpha.Opacity += -do_step;
  } 
  else
  { 
   clearInterval(obj.doing);
   obj.filters.Alpha.Opacity = min_opacity;
   obj.doing = false;
  } 
 } 
 function up_alpha(obj_index)
 {
  var obj = document.all[obj_index];
  
  if(obj.filters.Alpha.Opacity<max_opacity)
   obj.filters.Alpha.Opacity += do_step;
  else
  { 
   clearInterval(obj.doing);
   obj.filters.Alpha.Opacity = max_opacity;
   obj.doing = false;
  } 
 }
 
 function showMenu(menu)
 {
 	//menu.style.visibility='visible';
 	menu.style.display="";
 }
 
 function hideMenu(menu)
 {
 	//menu.style.visibility='hidden';
	menu.style.display="none";
 }