Thx for the feed-back.
Actually I now managed to emulate this function :
1. Start by tagging the Thoughts you want to show in that particular view with a specific tag ("Tag_View1").
2. Select all thoughts that do not have the tag and make them private
3. Stop showing private thoughts
A bit cumbersome but works. The problem is switching between views, which takes time...
However, this shows that implementing this in the software should be quite simple as all the functional bricks are already there...
Any hope to get it in a reasonabe future ?