Use this command to close all windows that contain the active document. Strawberry Prolog suggests you to save the changes made to your document before you close it. If you close a document without saving it, you lose all changes made since the last time you saved it. Before closing an untitled document, Strawberry Prolog displays the Save As dialog box to suggest you to name and save the document.
 

You can also close a document by using the Close icon on the document's window, as shown below: