There was question how to create these neat "blue boxes" that represent a link to a user name and also notify the user that his name has been mentioned in a post.

"Blue box":

@KhunBENQ

 

Simply type a "@" sign followed by the user name.

You can slowly type the user name letter by letter and a list will be built to select from.

The list will decrease in size the more letters you have typed ("incremental search").

 

Could look like this:

 

 

If you hover with the mouse over the box a popup with some information about the user will appear.

 

 

Nice, didn't know that.  Thanks.