fix flat/thread switch
fix flat/thread switch

A previous bug fix broke the flat/threaded switch in list view.
This implements a workaround for that.

jimjag/ponymail,quenda/ponymail,rbowen/ponymail,rbowen/ponymail,quenda/ponymail,jimjag/ponymail,jimjag/ponymail,jimjag/ponymail,rbowen/ponymail,quenda/ponymail,Humbedooh/ponymail,Humbedooh/ponymail,Humbedooh/ponymail