The next two features allow you some control over which objects are shown in the event wizard and to categorise them.
Here's what's in Common for the properties of a Sprite:
The bottom two are the ones we're interested in. The first, 'show in editors' will allow you to control whether the object is shown in the event wizard. For alot of background objects and scenery, you won't ever want to run actions or conditions from them, so hide them to avoid clutter.
The second, 'category' allows you to type in a category name for each object. Perhaps the best way to explain this is with a screenshot.
Each individual category name will create a new category in the event wizard, allowing much easier 'at a glance' selection and overviewing.