Does the rightside column show up also when there is no sidebar? As empty space?

Hi!
I'm using 5.1, which means I can not easely install and test this module.
I would like the possibility of having a third right coulumn showing up on some pages where I have such extra content related to a story. In these cases I want to have the 3 column layout, but when there is no sidebar I don´t want to stay in the 3 column layout as there is no block in the right sidebar (or only an empty block?).
Many thanks!
Sten