GM_registerMenuCommand() accelerator tester

gm-rmc-accelerator-tester.user.js

// ==UserScript==
// @name           GM_registerMenuCommand() accelerator tester
// @namespace      http://arantius.com/misc/greasemonkey/
// @description    A flexible test script for examining if/how GM_rmc's accelerator keys work
// @include        about:blank#GM_rmc
// @resource       ui.html https://gist.github.com/raw/898642/ui.html
// ==/UserScript==

var windowId = String(Math.random()).substr(2);

document.body.innerHTML = 'Window ID: '+ windowId 
    + GM_getResourceText('ui.html');

var registerButtonEl = document.getElementById('register');
var modifiersContEl = document.getElementById('modifiers');
var acceleratorEl = document.getElementById('accelerator');

registerButtonEl.addEventListener('click', function() {
  var modifiers = [];
  var inputs = modifiersContEl.getElementsByTagName('input');
  for (var i = 0, input = null; input = inputs[i]; i++) {
    if (input.checked) modifiers.push(input.value);
  }
  var accelerator = acceleratorEl.value;
  GM_registerMenuCommand(
      'Menu Command w/ accelerator: ' + accelerator + '+' + modifiers.join('+'),
      function() { 
        alert('You pressed ' + accelerator + '+' + modifiers.join('+')
            + '\nIn window: ' + windowId); 
      },
      accelerator, modifiers.join(' '),
      accelerator // re-use for access key
      );
}, false);

ui.html

<br>
<br>
<table>
<tr>
  <td valign="top">Modifiers:</td>
  <td id="modifiers">
    <input type="checkbox" value="shift"> Shift<br>
    <input type="checkbox" value="alt"> Alt<br>
    <input type="checkbox" value="meta"> Meta<br>
    <input type="checkbox" value="control"> Control<br>
    <input type="checkbox" value="accel"> Accel<br>
    <input type="checkbox" value="access"> Access<br>
    <input type="checkbox" value="any"> Any<br>
  </td>
</tr>
<tr>
  <td>Accelerator key:</td>
  <td><input type="text" size="1" maxlength="1" id="accelerator"></td>
</tr>
<tr>
  <td></td>
  <td><button id="register">Register this menu command</button></td>
</tr>
</table>