Behaviour of an interface or a component can be made visible in a state chart.
The state chart for the model in focus can be found under State Chart View in the Design perspective.
Clicking on a state or on a transition highlights the place in the model editor where the respective behaviour is specified:
The position of the states and of the transitions can be changed by dragging the respective item.
In case there are multiple interfaces and/or components in one file, the state charts for each of them can be shown by clicking on the "Click to Switch Available Diagrams" button on the top right (see picture below) or select the interface or component from the drop down list that will be shown when clicking on the drop down arrow right of the button.