CIGAL Reference Manual, Chapter 4 (Variables): vwindow
usage: vwindow = value
VWINDOW is a bit-flag controlling the active video display window (0 or 1). The two video windows are used for text display, with dimensions defined by the internal matrix variables ^^0 and ^^1. Normally, commands and short printed messages are entered and displayed in window 0, whereas longer printed output (such as HELP messages) are displayed in window 1. If window 1 has not been initialized, all text is displayed in window 0.
VWINDOW can be set as follows:
VALUE MEANING 0 Use window 0; Switch to window 1 as specified by WFLAGS (this is the normal setting of VWINDOW) 1 or 3 Use only window 1 (either 1 or 3 sets VWINDOW to 3 -- see meanings below) 4 Don't use window 1 -- Use only window 0 The meaning of VWINDOW is a 3 bit flag of the form: BIT VALUE MEANING 0 0/1 Which window (0 or 1) is currently active 1 0/2 Which window is the default display 2 0/4 Whether to suppress switching to window 1 (1=don't use window 1; 0=allow use of window 1)