Honest answer
Yes its possible
- SMF is open source so if you have the knowledge you could possibly change just about anything you want.
Do I know how to do this on flat pages?
Yes it would be a case of adding another button and an anchor to the top of the page.
Do I know where to insert this in the SMF templates?
No -
its sometimes a nightmare trying to find the correct templates and change anything since theres millions of lines of code, and its not always presented in a format thats easy to read.
Changing the header file (ie the top bit you see) is okish since I normally do that in html first - then just insert that straight into the header file which is separate and doesnt touch any of the main sections.
Aside from changing the images and CSS for the colours and fonts etc, I havent ever delved deep into the structure of the software itself. :/