fixed a bug in the core that caused EnvelopeContainer (and possibly other ContainerViews) to redraw (and recompute) their entire content every time the cursor was set to another position

Signed-off-by: Maximilian Marcoll <quince@maximilianmarcoll.de>
changes


Signed-off-by: Maximilian Marcoll <quince@maximilianmarcoll.de>
changed EnvelopeGate so that it creates a new Envelope instead of overwriting the old one


Signed-off-by: Maximilian Marcoll <quince@maximilianmarcoll.de>