Posted by a ceTe Software moderator
Hello,
The behavior you are describing is not a bug. The “Minimize” button minimizes the active pane (bookmark or thumbnail) but the pane itself is still active, hence the VisibleNavigationPane property remains unchanged and this is expected behavior. On the other hand, when you click on the Bookmarks or Thumbnail icon to close the pane, the pane is then deactivated, hence the VisibleNavigationPane property returns None.
Thanks,
ceTe Software Support Team.