Working with Windows
You can make the contents of the active window private. You can also read contents of windows that have previously been made private.
Note: The window operations are not supported on some versions of Windows. The Window menu therefore is not always available. If the active window is not supported by Encryption for Email, then the Window menu is unavailable.
The Window submenu contains the following option:
Sign, as described in Digitally Signing Text in the Active Window