Opera contains a really effective popup blocker built into the browser that can block the popups that you don't want while allowing those that you do. All that you have to do is to configure it to suit what you want.
The first step is to turn the popup blocker on. You do this by selecting Preferences from the Tools menu and going to the General preferences page. In the middle of the page is a section asking you to "Choose how you prefer to handle popups". Set this to Block Unwanted Popups.
Now all of the automatically generated popups will be blocked but unfortunately due to the way that some pages are coded some of the popups that you do want may also be blocked. You can tell when there is a blocked popup because a message pops up at the top right cormner of your browser for a few seconds telling you that the browser has blocked a popup.
You can get the browser to open the blocked popup by clicking on that message which is okay to handle a one off situation where a popup has been blocked that should not have been but it would be really annoying if we had to do that every time.
Fortunately the browser allows us to override the global popup blocker on a site by site basis. To do this right click somewhere on the web page that has the blocked popup that you don't want blocked and select Edit Site Preferences from the context menu. You can now change the popup settings for that site only back to Open all popups.
The popup blocker will now permit all popups on those sites that you have specifically requested for it to allow popups on while only allowing those that it identifies as having been specifically requested for all other sites. For those rare occasions where it still blocks popups that you want you can still open them by clicking on the blocked message in the corner of the browser.
This article written by Stephen Chapman, Felgall Pty Ltd.