There are two types of tools in Alias: momentary and continuous.

Momentary functions, such as Pick > Nothing, perform an operation once, every time you select the function.

A continuous function, like Pick > Object, remains selected and highlighted, letting you use the function repeatedly without reselecting the button. To stop a continuous function, just select another continuous function.

You can select momentary function without interrupting a continuous one. When the operation of a momentary function is finished, the system reverts to the operation of the last continuous function. For example, if you select Pick > Object and after picking a few things, want to view the scene in another window, select Layouts > Top. After the Layouts operation is performed, you will automatically continue in the Pick operation without having to reselect the Pick button.