Scrolling Tremula container and reaching website header/footer

I am experimenting with the Pinterest style layout.
I also have a website navigation header and footer, horizontal/vertical layout switcher.

Scrolling is locked over tremula container, and looks like I must set Tremula container height.
I cannot push the website header up as with normal scrolling and cannot reach the website footer.

Start by reproducing the scrolling behavior with a Tremula container, website navigation header and footer, and the horizontal/vertical layout switcher. Determine how the container's height and scroll locking affect page navigation; done means the header can move out of view and the footer is reachable while the layout switcher continues to work.

Written by the indexing model from the issue text.