Now I found the Start Folder Tree at..., and set it to Desktop. That keeps the tree focus closer to the folder where I am normally working.
The ideal action would be if DOpus would use the find folder in a virtual way, without changing the tree focus to that folder. The lister tab that named "Find Results" should be an adequate flag for users that what is displayed is not the user's current folder (which would be shown as an inactive selection in the tree). Also, a new tab should be created for the Find results, instead of changing the user's current tab to Find Results.
JMO, but I think this approach would be much more user-friendly and productive.