Main toolbar > Selection Filter
The Selection Filter list lets you restrict to specific types and combinations of objects that can be selected by the selection tools. For example, if Cameras is selected, you can select only cameras with the selection tools. Other objects do not respond. This is useful as a quick method of freezing objects when you need to select objects of a certain type.
Use the drop-down list to select a single filter. Select Combos from the drop-down list to use multiple filters from the Filter Combinations dialog.