remove strut when property is withdrawn
remove strut when property is withdrawn

CCBUG: 1133

luebking/fluxbox,Arkq/fluxbox,Arkq/fluxbox,luebking/fluxbox,Arkq/fluxbox,Arkq/fluxbox,luebking/fluxbox,luebking/fluxbox,Arkq/fluxbox,luebking/fluxbox