In the File
menu, select Close All.
or
In the Standard
toolbar, click on the Close
All 
icon.
It's possible to close all open documents at once. If one of the documents has not been saved, or has been modified since the last time it was saved, CuteHTML Pro will ask you to save it before you close it.
To close all open documents:
In the File
menu, select Close All.
or
In the Standard
toolbar, click on the Close
All
icon.
If any of the documents has undergone changes which have not been saved, a message will remind you to save it. If you close a document that has never been saved, a message is displayed so that you can save it under the name of your choice.
You can also use the shortcut CTRL+ALT+F4 (Refer to list of shortcuts).