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This documentation relates to Opera's now deprecated .oex Extension API framework for Opera versions <= 12.15 and also provided by our OEX2NEX shim library.

For the latest Opera Extensions API documentation for Opera versions > 12.15 please consult the latest Opera Extensions API documentation online.


The width of the popup window; by default, the width is 300px. Note that this attribute is set in the background script as part of the ToolbarUIItemProperties object. See the Browser Toolbar guide.


Number width


// The background process (e.g. '/background.js'). 

// Set options for the button
var UIItemProperties = {
  disabled: false,
  title: 'Opera Extension',
  icon: 'images/icon_18.png',
  popup: {
    href: 'popup.html'

// Set the popup's height to 480 pixels
UIItemProperties.popup.width = 200;

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