anchor.diff:  	  document.all.btn_role.disabled=true;
   	}
     }else{
  -    document.all.btn_del.disabled=true;
   	  document.all.btn_modify.disabled=true;
   	  document.all.btn_user.disabled=true;
   	  document.all.btn_role.disabled=true;
  
positive.code: function checkOperation(form){
    num = getCheckedBoxNum(form,"id");
    if(num>0){
      document.all.btn_del.disabled=false;
  	if(num==1){
  	  document.all.btn_modify.disabled=false;
  	  document.all.btn_user.disabled=false;
  
negative.code: <table width="100%" border="0" align="center" cellpadding="0" cellspacing="0">
    <tr> 
      <td width="50%"> <input name="btn_add" type="button" value="增加" class="button" onClick="javascript:add();"> 
        <input name="btn_modify" type="button" value="修改" class="button" onClick="javascript:modify(this.form);" disabled>
        <input name="btn_user" type="button" value="用户管理" class="button" onClick="javascript:users(this.form);" disabled>
        <input name="btn_role" type="button" value="角色设置" class="button" onClick="javascript:roles(this.form);" disabled>
  