91 Avant driver's window disappears into door all by itself

[Ed Kellock]

After GF returned home this afternoon with Pentosin gushing from the
headlight of the 90 V8, we decided to take the 91 Avant to dinner.  When I
opened the door, the previously closed window disappeared into the door
all by itself.  It is no longer connected mechanicaly to anything inside.
I've read about this, but never had the pleasure in person.  Nasty repair?

Ed