Selecting objects conforms to a selection style that is common to most Mac applications.
Use click and drag to specify a rectangular selection area. Drag to the left for a crossing selection, or drag to the right for a window selection.
Each time you select one or more objects, it automatically clears the previous selection. To add objects to the previous selection, hold Shift as you select them.
You can change the behavior of object selection in the Application Preferences dialog box by clicking Cursor & Selection (the OPTIONS command).