function disableCtrlKeyCombination(e) {
    var forbiddenKeys = new Array('a', 'n', 'c', 'x', 'v', 'j');
    var key;
    var isCtrl;
  
    if(window.event) {
      key = window.event.keyCode;
      if(window.event.ctrlKey) {
        isCtrl = true;
      } else {
        isCtrl = false;
      }
    } else {
      key = e.which;
      if(e.ctrlKey) {
        isCtrl = true;
      } else {
        isCtrl = false;
      }
    }    
    if(isCtrl) {
      for(i=0; i<forbiddenKeys.length; i++) {
        if(forbiddenKeys[i].toLowerCase() == String.fromCharCode(key).toLowerCase()) {
          return false;
        }
      }
    }
    return true;
  } 
  
  function click(e) {
    if(document.all) {
      if(event.button == 2) {
        return false;
      }
    }
    if(document.layers) {
      if(e.which == 3) {
        return false;
      }
    }
  }  
  
  if(document.layers) {
    document.captureEvents(Event.MOUSEDOWN);
  }
  
  if(document) {
    document.onmousedown=click;    
    document.onkeypress=disableCtrlKeyCombination;
    document.onkeydown=disableCtrlKeyCombination;
    document.oncontextmenu=function() { return false; };
  }