There are two extremely useful purposes for selecting an empty space in the explorer. Doing so deselects the current item if the skybox isn’t available and allows box selecting a group of items. When Studio 2013 was first released, the selection box for items in the explorer covered the whole explorer horizontally, contrary to in the previous build of Studio in which the selection boxes were the names of the object. ROBLOX quickly fixed this, so it’s clear that the selection boxes are intended to end at the end of the object’s name.
Clicking on the right will deselect the object or allow drag-selecting a box in the explorer as expected:
However, it appears that the selection boxes do not terminate at the end of the name of the object. They terminate at the end of the longest object visible in the explorer. Objects inside objects shift over horizontally – an object deep in a tree of other objects will be pushed far horizontally. Because of this, it becomes the longest object and the explorer, and because the explorer terminates the selection boxes at the end of the longest item, you become unable to deselect items by clicking in the explorer:
Selection boxes in the explorer should terminate at the end of the object’s name and not the longest object’s name.