//obtenir la propriété style d'un objet
function getstyle(id,prop){ 

if (document.getElementById(id).currentStyle){ 

return document.getElementById(id).currentStyle[prop]; 

}else if (window.getComputedStyle){ 
 
 return document.defaultView.getComputedStyle(document.getElementById(id),null)[prop]; 
 
}

return  css_style(id,prop);
} 

function css_style(id,prop) {
	  var t = document.all(prop);	  var res=t.style[id];
	  
	  if ((res==null) || (res=='') || (res=='undefined')) {
	    var classe = t.className; var regles = 'rules';
	    
	    for (var sSheet=0; sSheet < document.styleSheets.length; sSheet++) {
	      
		  for (var rule=0; rule < document.styleSheets[sSheet][regles].length; rule++) {
		  
		    var currentClass = document.styleSheets[sSheet][regles][rule].selectorText.substring(1);
	        if (currentClass == classe) {  return document.styleSheets[sSheet][regles][rule].style[id];  }
			
	      }
	    
		}
	  }
	  
	  return  res;
}


//gestion des ID
function remplace_id(id){
	var tid=id; i=0;
	while (document.getElementById(tid)) {
		tid=id+'_'+i;
		i++;
	}
	
	return tid;
}