How to make object invisible for mouse

Hello,

I have many objects loaded in a scene (part of a SortingVisual3D) and added a manipulator to each of them. Everything works perfectly.

Now I want to surround them by a transparent cylinder. Also this works.

The problem I have now is that the manipulators are not useable when the objects are in the transparent cylinder because the mouse is captured by the cylinder.

Is there a way to make the box invisible for mouse operations?

I am using Helixtoolkit for C# WPF