strhelper_lan::set_background

Source: stream/helpers/lan/strhelper_lan__set_background.pro

 strhelper_lan::set_background
        Set the backgrounds for a lan rates stream.

 Usage:
        strid->set_background, bglevel

 Argument:
        bglevel The background level (or levels) for the stream.

 Keywords:
        before  If set, then bglevel is a scalar with the level before
                the shift.
        after   If set, then bglevel is a scalar with the level after
                the shift
        default If set, then restore the background settings to the
                values in the IDF.DAT file.

 History:
        Original: 24/11/99; SJT
        Moved to strhelper_lan class: 21/12/99; SJT
        Clear ready flag in parent if needed: 11/7/00; SJT
        Add default key: 17/4/02; SJT