A ClearWin window (no '+') refers to a window created to contain output
that would have gone to the screen if the program were not a Windows
application. The name refers to the fact that the original ClearWin only
created such relatively primitive windows. A ClearWin window is still
useful for debugging purposes, and may be properly embedded in a format window
using %cw. Keyboard input can also be taken from a ClearWin window, but
this is not recommended in finished programs.