add a new state
in the state pane on left, click the 'add'('+') button to create a state.
in prompt dialog, enter a state name and click 'OK' to comfirm.
note: when you create a new project, a 'preload' scene will create automatically. this state is used to preload the resources of game. this state should not be removed.
remove a state
to remove a state, click the 'remove'('X') button.
in confirm dialog, click 'OK' to remove state files from disk. if you want to keep the state files, click 'Cancel' to cancel remove state files.