Disabled Firefox Add-on ActionButton not grayed out <p>When creating a Firefox Add-on <code>ActionButton</code> <code>disabled</code>, e.g.,</p> <pre><code>var button = new ActionButton({ id: 'my-link', label: 'My label', icon: { '16': './icon-16.png', '32': './icon-32.png', '64': './icon-64.png' }, onClick: handleClick, disabled: true }); </code></pre> <p>the button indeed isn't clickable and doesn't produce any events, but the icon does <em>not</em> appear grayed out as advertised in <a href="https://developer.mozilla.org/en-US/Add-ons/SDK/Low-Level_APIs/ui_button_action" rel="nofollow">the documentation</a>.</p> <p>Any ideas as to why this might be?</p>