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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 readonly collapsed attribute exposes the collapsed state of the browser tab group. On getting, the attribute returns true if the browser tab group is collapsed, otherwise it returns false.


When specified as an item in a BrowserTabGroupProperties object, the collapsed property indicates the desired collapsed state of a browser tab group. The value true indicates that the tab group should be collapsed, and false indicates the tab group should be expanded.

When creating a browser tab group, if this property is not specified the default behaviour is the same as specifying false.

When updating a browser tab group, if this property is not specified, the default behaviour is to leave the collapsed state unchanged.



readonly boolean collapsed


boolean collapsed


The following example creates a button on the browser toolbar. When the button is clicked, a tab group is created containing two tabs. Then the new tab group is collapsed.

// 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",
  onclick: function() {
    // Create two tabs with specified URLs
    var tab1 = opera.extension.tabs.create({url: 'http://www.reddit.com/'});
    var tab2 = opera.extension.tabs.create({url: 'http://www.digg.com/'});
    // Create a tab group containing the above two tabs
    var tabGroup = opera.extension.tabGroups.create([tab1, tab2]);
    // Collapse the new tab group
    tabGroup.update({collapsed: true});

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