Opera's Pop-up Blocker is integrated into the browser, much like the Pop-up blocker for Internet Explorer. To disable the Pop-up Blocker:
From the Tools menu, select the Preferences option. The following window will appear:
Click on the Windows option in the left-hand list in the window.
Select the Open all pop-ups option in the Pop-ups list.
Click the OK button to close the window.
Once you are finished, you can go back into the menu again to turn on the Pop-up Blocker.