This routine will flush the graphics command buffer. This routine
is called implicitly whenever the routines window_intype or
intype are called. The user may also call this routine explicitly
in order to force immediate transmission of any buffered commands.
Such a call might be desirable after issuing a series of graphics
commands and before embarking on a time-consuming calculation.
This function requires the following include files:
LXFLSH, wn_point(_c), wn_point_set, wn_vector(_c), wn_text(_c),
wn_box(_c), wn_circle(_c), wn_circular_arc_c, wn_polygon_c,
wn_symbol(_c), wn_symbol_set, wn_grid(_c), wn_quick_grid,
wn_axis_grid(_c), wn_axis_label(_c), wn_display_value(_c), wn_erase(_c),
wn_external_text(_c), wn_external_colored_text_c, intro_graphics_windows