Drop zones in iDVD!
This might also work with iDVD 06, but I am not sure. I only used it in the latest version. There are two views in iDVD, the standard view and the hierarchical tree view. The hierarchical view will let you easily manage menus and submenus. But that is not what I want to talk about. What is not obvious is that you can double-click on the background (in standard view) and the background will move backwards in 3D. You will then clearly see every drop zone and what is in it. Here is an example: