var brws = ( parseInt(navigator.appVersion)==4 );
var icn = new Array('top_btn01','top_btn02','top_btn03','top_btn04','top_btn05','top_btn06','top_btn07','top_btn08','top_btn09','top_btn10','top_btn11','top_btn12','top_btn13');
var icn_up = new Array(icn.length);
var icn_dw = new Array(icn.length);
var icn_cl = new Array(icn.length);

for(i=0;i<icn.length;i++){
  icn_up[i] = new Image();
  icn_up[i].src="img/"+icn[i]+"_over.gif";
  icn_dw[i] = new Image();
  icn_dw[i].src="img/"+icn[i]+"_off.gif";
  icn_cl[i] = new Image();
  icn_cl[i].src="img/"+icn[i]+"_over.gif";
}

function up(tgt){ 
    brws && (tgt.src = icn_up[find_no(tgt.src)].src);
}

function dw(tgt){
    brws && (tgt.src = icn_dw[find_no(tgt.src)].src);
}

function cl(tgt){
    brws && (tgt.src = icn_cl[find_no(tgt.src)].src);
 }

function find_no(str){
  for(i=0;i<=icn.length;i++){
    if(str.indexOf(icn[i])>0){
      return i;
    }
  }
}