OTTAWA - Just as quickly as Canada's privacy czar handed Facebook a passing grade for changes it made to information controls, she's begun investigating another set of issues involving the constantly evolving social-media behemoth.

Privacy Commissioner Jennifer Stoddart said Wednesday that she's satisfied the network responded to concerns she raised in 2009 about the sharing of private user information with third parties — creators of games and other applications, for example. Facebook participants have also been given a clearer explanation of its privacy policy.

The changes instigated by concerns raised in Canada affected what the 500 million-plus users of Facebook around the world see when they log on.

"I think it took a while for Facebook to take us seriously," Stoddart said in an interview.

"It was a very long road to where we are. They kind of took a side track and now in the spring they got on the main track and came back and so we finally reached a satisfactory conclusion."

But Stoddart says she is already looking into other complaints filed about Facebook. One of them involves the "like" button that users are invited to click on below a description of a product or service.

Once a user does that, the individual or organization who controls that product can actually gain access to the user's "wall" and post information at will. If given permission, they can also tap into a person's private profile data.

Stoddart is also looking into messages that are sent to non-Facebook users asking them to join the network.

"There's a lot of innovation that doesn't look at privacy norms, either ones that are generally accepted or ones that are actually laws," she said. "As Facebook continues to recreate itself and deals also with other conglomerates like Google for consumer attention, I'm sure there are other issues coming up."

Even since Stoddart started her investigation, Facebook's business model has changed, further integrating the network into the broader Internet and other social-networking sites.

And there's no sign of an end to the evolution.

Facebook's creator Mark Zuckerberg described to The New Yorker this month a scenario where the reading, TV-watching and purchasing habits of users would be increasingly available for viewing by other friends: switch on the television in the future, and you'd get a list of what others were watching.

Zuckerberg told the magazine that privacy was a "third-rail issue" online.

"We realize that people will probably criticize us for this for a long time, but we just believe that this is the right thing to do," he said of the network.

The organization that filed the original complaint with Stoddart, the Canadian Internet Policy and Public Interest Clinic, says it's important to note she has not issued an endorsement or clean bill of health to the network.

Executive director David Fewer said he likes that there is more transparency on Facebook with regard to how information is used, and that there are more tools available to users to lock down their information.

But he said Facebook remains a moving target for privacy advocates.

"One of the things that bothers me about Facebook is that it seems to have adopted the model to forge forward and fix it later," said Fewer. "If they want to do something and there are privacy issues, they'll fix it later."