function kdown(e) {var msg =""; var flg = 1;
switch(window.event.srcElement.tagName){
case "INPUT" :if(event.srcElement.type != "text" && event.srcElement.type != "password"
&& event.keyCode!=9 && event.keyCode!=16 && event.keyCode!=32){return false;}else{flg=0;}break;
case "TEXTAREA" :flg = 2;break;
case "SELECT" :flg = 0;break;
case "A" :flg = 0;break;
}
switch(event.keyCode){
/* case 8 :msg = "BS";break; バックスペースは解除*/
case 13 :msg = "Enter";break;
case 27 :msg = "Esc";break;
case 78 :if(event.ctrlKey){msg = "Ctrl+N";}break;
case 82 :if(event.ctrlKey){msg = "Ctrl+R";}break;
/* case 116 :msg = "F5";break; F5アタックは解除*/
case 122 :msg = "F11";break;
}
if(event.altKey){msg = "Alt";}
if (flg == 0 ){switch(event.keyCode){case 8 :msg = "";break;case 133 :msg = "";break;}}
else if (flg == 2 && event.keyCode==13)msg = "";
if(msg != ""){event.keyCode = 0;return false;}else{return true;}
}
document.onkeydown = kdown;
/* special thanks http://www.geocities.jp/knight_of_crusader/tag/nokey_b.html */