A: 

Try display = '' instead of either display = 'block' or display = 'none'.

Sjoerd
Thank you. I've tried it but nothing...
bobighorus
+1  A: 

Sounds to me like a bubbling problem.

http://www.quirksmode.org/js/events_order.html

Khan
thanks for your answer. so have you got any idea for edit and fix my code?
bobighorus
My conclusion is that is not a bubbling problem but some css property bug in IE7..
bobighorus
+1  A: 

You're not even using MooTools' syntax. If you would, use mouseenter/mouseleave instead of mouseover/mouseout.

nav_divs.each(function(el){
  el.addEvents({
    mouseenter: function(){
      this.getElement('ul').setStyle('display', 'block');
    },
    mouseleave: function(){...}
  });
});
Oskar Krawczyk
Thank you so much for your answer; I've used your good code but still in IE7 doesn't work...all is ok in the other browsers...nav_divs.each(function(el){ el.addEvents({ mouseenter: function(){ this.getElement('ul').setStyle('display', 'block'); }, mouseleave: function(){this.getElement('ul').setStyle('display', 'none');} });});
bobighorus
As I just said I tried also with a simple jQuery function but nothing; definitely it's not a matter of JS...
bobighorus
Hmm, in that case I'm unsure what are you trying to achieve. Btw. `.nav { position: relative }` ?
Oskar Krawczyk
I've tried also this but nothing changes...mmm...
bobighorus
Yeah, I was guessing since I have no idea what you're trying to do. Put up an example on jsfiddle.net.
Oskar Krawczyk
A: 

i agree, this is not a bubbling problem, it is more than likely to do with the CSS you are applying to the ul.

top: 0 and left: 0, is it meant to do that on an absolute element? dunno, unless ul has to be sown at top left of the viewport (and then -50px via margin-top above would make it outside viewable area).

http://www.jsfiddle.net/uAAge/

By removing the top: and left: declarations from the css class it's fine as a relative popup (tested in ie7, ff3 and chrome). if you need to offset it now so it's better positioned around the trigger element, use marginTop and marginLeft instead.

Dimitar Christoff
Thanks Dimitar.I think that your contribute is definitely near to the solution...I tested your code with IE7 and all is ok; I noticed that you simply delete "top" and "left" istructions. So I've made this change in my css but still nothing!!!I've investigate the problem and I've found that the ul block is visible only with negative margin-top (top direction) but I need positive margin-top.I've published my work here: http://bit.ly/dzy4ny .Thank you in advance for your help.
bobighorus