Comment Section in Blogs/Articles

Hi,

I had a problem today with the blogs section... Today i forgot to login to my account, before login i visited some blogs and typed a big comment on to the comment section and clicked on the Submit button... Later it asked me for the username and pwd... Once i gave the credentials it went back to the blog which i opened but i surprised to see that the long comment which i typed was not there.

we should have a system that it should not allow to comment unless we login, else if it allows after we comment and give the login credential the comment should be cached and be inserted..

Please suggest!!!