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
// ==/UserScript==

ui.html

<table>
<tr>
  <td>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>