Select multiple itens at ProjectExplorer
Disable update state's labels automatically

For add custom labels to states disable the macanism of auto recalculating labels calling the method setAutoUpdateLabels(false);
Set the view type of Transition for new transitions.

Use the method setViewType(int) at TransitionBuilder to set the view type of the transition. The parameter can be TransitionViewFactory.LINEAR or TransitionViewFactory.SEMI_CIRCLE