Private Window content visible by next player

Hi, is this a bug ?

VASSAL Version 3.2.17
Operating System : Max OS X Sierra
Module contains :
1 Map Window, used as a main map
4 Map Windows, used as players maps, visible by all
4 Private Windows, used as players cards, visible by all, but only modifiable my owner
4 Private Windows, used as players hidden hands, not visible by non-owners
The 4 Private windows not visible by players are impossible to select from the Main toolbar for non-owners - OK.
When the active player retires leaving his Private Hand open, the window remains visible for other players.

Any idea about how to ensure that clicking the Retire button will hide/close the private windows for next user ?