Thanks, I know what it means and I know that I can display other module with content to fill the white space, but that is not the solution for me. I don`t want other stuff instead of the white space; I just wont the template position to collapse if empty. As far as I know the actual display of the modules, including the module position, is entirely handled by the template, not by Joomla itself, that`s the reason I posted my question here.
If you take a look at the attached image, you will see that there is an empty DIV (id="gkSidebar" class="gkOnlyOne") 307px x 0px, occupying that position.
How can I change that?
Is the countModules method (or something similar) used in the template to determine if a module is in fact set for the position?