Step Run Window

The Step Run Window displays up to 15 configurations at a time. Each configuration consists of the current state and the remaining input (and the stack in the case of PDA) for automata or the current state and the relevant part of the tape (or tapes in the case of TTM) for Turing machines)
Configurations can be selected or unselected by clicking on them. Selected configurations are shown darker. Invalid configurations (i.e. which cannot be expanded any more) are marked with a red cross in the upper left corner.
The Run Window Buttons:

Kill | Delete all selected configurations.
Freeze | Freeze all selected configurations. (the frozen configurations will not be expanded) (a frozen configuration is marked with a snow flake in the upper left corner)
Thaw | Un-freeze all selected configurations.
Trace | View the path of the selected configuration. (exactly one configuration must be selected)
Step | Expand the current set of configurations by applying the next transitions.
Restart | Restart the step run from the start state.
Quit | Quit the Step Run Window and return to the building canvas.