Platform dependant toolbar icon for Opera extensions

platformToolbarIcon.js

var toolbarButton, toolbarButtonProperties;
function createToolbarButton()
{
    var toolbarIcon = ((~window.navigator.platform.indexOf('Mac')) ? 'macIcon.png' : 'otherIcon.png') ;
    toolbarButtonProperties = {
    disabled: true,
    icon: toolbarIcon,
    onclick: buttonClickHome,
    title: 'Site Home'
  },
  toolbarButton = opera.contexts.toolbar.createItem(toolbarButtonProperties);
  opera.contexts.toolbar.addItem(toolbarButton);
}