CSS+DIV实现下拉列表

< html >  
< body text = " #ffffff " >  
<!----------- 菜单js内容 ---------->  
< script language = javascript >  
ie4 = (document.all) ? true : false ; 
ns4 = (document.layers) ? true : false ; 
function toExit(){ 
var args = toExit.arguments; 
var visible = args[ 0 ]; 
if (ns4){ 
theObj = eval( " document.layers[\' " + args[ 1 ] + " \'] " ); 
if (theObj)theObj.visibility = visible; 
} 
else   if (ie4){ 
if (visible == ' show ' )visible = ' visible ' ; 
if (visible == ' hide ' )visible = ' hidden ' ; 
theObj = eval( " document.all[\' " + args[ 1 ] + " \'] " ); 
if (theObj)theObj.style.visibility = visible; 
} 
} 
</ script >  
<!------- 这是菜单层 ------->  
< div id = boysoft onMouseOut = " javascript:toExit('hide','boysoft') "  onMouseOver = " javascript:toExit('show','boysoft') "  
style = " HEIGHT: 20px; LEFT: 9px; POSITION: absolute; TOP: 36px; VISIBILITY: hidden; WIDTH: 30px; Z-INDEX: 1; background-color: #666666; layer-background-color: #666666; border: 1px none #000000 " >  
< select onchange = " change(this) " >
     < option value = " 1 " > 全选 </ option >
     < option value = " 2 " > 反选 </ option >
     < option value = " 0 " > 取消 </ option >
</ select >
</ div >  
< a onMouseOver = " javascript:toExit('show','boysoft') "   >< font color = " #0000FF " > 选择 </ font ></ a >  
</ body >