break;

case 90: //z

document.execCommand('Undo');

break;

case 89: //y

document.execCommand('Redo');

break;

default:

break;

}

event.keyCode = 0;

event.returnValue = false;

}

return;

}

function show_ln(){

var txt_ln = document.getElementById('txt_ln');

var txt_main = document.getElementById('txt_main');

txt_ln.scrollTop = txt_main.scrollTop;

while(txt_ln.scrollTop != txt_main.scrollTop) {

txt_ln.value += (i++) + '\n';

txt_ln.scrollTop = txt_main.scrollTop;

}

return;

}

function editTab(){

var code, sel, tmp, r

var tabs=''

event.returnValue = false

sel =event.srcElement.document.selection.createRange()

r = event.srcElement.createTextRange()

switch (event.keyCode){