Currently this tool doesn't support saving graph with unicode character.
I'm new to Java so I don't have ability to fix this.
Maybe someone can fix the saving mechanic to support Unicode properly.

More infomation:
Unicode characters are able to type, edit and show properly in graphs, but not when save to file.
Open a file with manual editing unicode file is not tested.

A string to test (a Vietnamese pangram):
"Do bạch kim rất quý nên sẽ dùng để lắp vô xương"