redundant border in NSStackview

Question

Good morning :)

I working with swift 4 for macOS and play the first time with NSStackViews. I build a litte example:

• NStackView
• includes three NSBoxes
• all boxes have a 1px border (different colors), which i setted via Storyboard.

The "beautiful" result:

I tried to show my problem in this picture. You can see that the first box has a blue, the second a green and the third a orange border.

In this case I have every time two border between the boxes. Example: Between the first and second box i have a blue/green border.

Is it possible to set only one border side? Something like: only top border or only left border?