Interesting. I really didn't think that would make a difference. I was just trying to establish a baseline. Well, we seem to have a baseline.
Yes, I can close my open workspace and create a file called "test.c". In that file, if I type "if(", the rest of the if statement is populated and the paren highlighting matches.
Yes, it would be helpful to post screen shots of any annomolous behavior you've reported. It's not that we don't believe you.
But we may be able to spot something that gives us a clue as to where to look.
You may want to start using SlickEdit projects. Much of the power in SlickEdit derives from Context Tagging. Without creating a project and associated workspace, we have no place to store the tags for your code, so we can't give you symbol previews or provide symbol navigation (Ctrl+Dot, Ctrl+/, and Ctrl+,). These are some of the most powerful features in SlickEdit. You can find more information on this in the User Guide: Help > Contents, then read the section on "Workspaces, Projects, and Files".
Paren highlighting and Syntax Expansion aren't dependent on tagging, so we should be able to figure this out anyway.