You have seen that symbols have the ability to alter their visual aspect using parameters and conditions. This ability is useful for creating rich graphic objects such as dials, or meters, for monitoring activities. Another useful aspect of GUI objects is to be able to respond to user actions using interactors. An interactor is used to create interactive objects by specifying how user actions can alter the value of a symbol parameter.

This mechanism works as a loop. A user interaction modifies the value of a parameter, this new value is processed by the symbol in order to give the appropriate visual feedback. Both actions in this loop are completely independent. That is, the interaction does not need to 'know' what the visual effect is.

A symbol interactor detects and processes input done by the user on a symbol. This is in the form of mouse events on the graphical representation of a symbol.

An interactor does one of the following:

The different kinds of interactions available are:

Discrete, Horizontal, Vertical and Rotation interactors work in the same way. They respond to a mouse event by changing the value of a symbol parameter. This means that, although the interactor is applied to a specific object, the change occurs to any object bound to the parameter. Push interactors use conditions to transform the object clicked. When a condition has been created for a push interactor, it can be used to make simultaneous changes in multiple objects.