First, be sure that the environment has fully loaded.
Click the appropriate tab—Player, Static, AI—so that it is blue.
Place the mouse pointer carefully over the >. Hold the mouse motionless while you click the left button.
Whenever there is no response, first click the Entity creation title bar—even if it is already blue.
The panels do not respond to selections unless they are first made the active panel—title bar is blue. Sometimes a panel may become inactive even though its title bar remains blue.
This explains why a double-click sometimes is needed—the first click actually makes the panel active.
