[Oberon] PO2013 - System.CloseTrack / System.ExtendDisplay

[Andreas Pirklbauer]

    > Now mark viewer3 and call System.CloseTrack
    > - It closes viewer 3 and grown viewer 2 and restores viewer 1 and 2 

Ah right. It actually does *more* than “just" the equivalent of System.Close
viewer 3 (as alluded to earlier): it also closes all viewers opened *on top*
of the grown viewer 2 as well -> so an entire stack of viewers “above” the
grown viewer is closed in a single step.

A neat feature.. but rarely used (I suspect?), as the average user
doesn’t necessarily think in stacked 3-dimensional window layouts.