Bring a foreground node in front of another foreground node

Continuing working on the diagram created in the following topic:

I have added nodes in the same diagram which now looks as follows:

Pink and Grey color nodes are “ForeGround” Nodes, while Light Green color nodes are “BackGround” Nodes.

Grey color node is the static node.

My requirement is, when i drag the diagram (Pink/Light Green color Nodes) from Right to Left, the part of these nodes (In Blue box) should not be visible on Static Grey color Node.