disabled field is always accessible.

Hi,

I have a xform page which contain disabled field. This field are visible but disabled by a CSS style like this:

.editApparitionContext.disabled
{
	display:inline;
	filter:alpha(opacity:50);
}

When i use tabulation (or mouse) to navigate accross my fields, it is possible to reach all the disabled fields. And if this field is a combo box, it is possible to access at its list.
It's very embarrassing for the user.

Does there exist a workaround at this problem?