By Opera Software

From Opera 15 onward, Opera 11 & 12’s extension format is no longer supported, and instead, we’ve switched to Chromium’s extension model. Check out our new documentation for developing extensions for Opera 15 and higher and start building your own extensions.


The getAll() method provides a way to obtain a window collection. When the getAll() method is invoked, the implementation must return an array of BrowserWindow objects representing each browser window that is currently open.




BrowserWindow[] getAll ()


The following example creates a button on the toolbar. When the button is clicked, the number of browser windows currently open is shown in the button's badge.

// The background process (e.g. index.html)

// Specify the properties of the button before creating it.
var UIItemProperties = {
  disabled: false,
  title: "Example extension",
  icon: "images/icon_18.png",
  badge: {
    backgroundColor: '#cc0000',
    color: '#ffffff'

// Create the button and add it to the toolbar.
var button = opera.contexts.toolbar.createItem( UIItemProperties );

button.addEventListener('click', handleClick, false);

function handleClick() {
  var windows = opera.extension.windows.getAll();
  button.badge.textContent = windows.length;

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