Here you can mainly save your DNA strings. In the top window bar you see the name
of the current file you are working on. If your current work wasn't saved until now,
it has the name "Unknown".
If you choose "Save" although the file hasn't got a name, you will be forwarded to the "Save as..." dialog.
With "Close" you close the window. If your work has not been saved but changed, a message appear where you
can choose to save it or not.
Attention: If you leave the window per "X" in the top right corner there won't be any warning. The data will be lost!