Mouse_area and scrollable interaction

I am trying to implement snap scrolling in my app.

I tried to catch event of scrollable. I need to scroll it manually in update function and this is causes loop of mouse scroll → scroll event → my scroll → scroll event → my scroll.

Then I tried to catch scroll events with mouse_area but got strange behavior.
If scrollable is inside of mouse_area than only scrollable send messages.
If mouse_area is inside of scrollable than both mouse_area and scrollable send messages.

What is expected behavior of mouse_area and scrollable? How can I intercept scroll events and not pass it to scrollable so I can manually scroll it?