Please shut down the application by clicking in the top right-hand corner of the window.
If you press ctrl-c in the terminal the program will take a long time to start up the next time you use it. If you turn off the computer while using the program the database files may become corrupted or unusable. If this does happen you will have to restore the database from a backup by deleting all the files in the solubility/db directory and replacing them with a previous saved backup.
Periodically you should save the database you are working on by making a copy of the entire solubility/db directory.