Templating

[eluser]CanadianBeef[/eluser]
I'm just curious...something I have not been able to determine reading the docs hitherto is how you templatize an applicaiton so each page follows similar navigation.

How do you handled situations where a login form might displayed on each page until an individual is logged in at which a "My toolbox" might replace it?

Do you use a HTML static template and "inject" the dyanmic body contents into the template using str_replace?

This would apply to both the body content and possible navigation in the case of login FORM's?

If you could point to an article on best practices in this regard I would appreciate it.

Cheers,
CB