Popups are windows which can be triggered by either a user action, or automatically by the page that you are visiting. Unfortunately, many web sites misuse popups, adding advertising and unrequested content when you visit a page. By default, Opera blocks unwanted popups (those popups you didn't ask for by clicking or selecting something on the page). To change these settings you can use Opera's quick preferences (press F12 to show):
The first two options always allow popups to open, either in the foreground (i.e. the popup becomes active above the page you were visiting) or in the background. We have described the default option already, and the final option turns all popups off. The default option is probably the best option for regular surfing. But what happens if a popup we wanted gets blocked? Well, Opera notifies us whenever it blocks a popup, and it saves these popups if we then choose that we wanted to see them. Popups are stored in the page bar trash menu. To see it in action, see the following animation:
By default, Opera uses an animated tooltip to notify when a popup is blocked, but you can easily disable these using Preferences » Advanced » Notifications. If the tooltip notification is disabled, only the Trash can colour will indicate if a popup has been blocked.
When surfing, one closes a page by mistake, or wants reopen a page closed some time ago. Opera now put closed pages that were previously closed in the browsing session in the Page bar Trash can. To reopen any page we previously closed, we can even simply type CTRL+ALT+Z anytime, or CTRL+Z when the focus is outside textboxes, to "undo" the last page closure.