Hi Mike,

> oh, when I use "boole mix" instead of trimm
> it works!
>
> ?

If you do indeed have a self-intersecting curve in some cases the weird leaking effect can be contained in a very small area and be hard to notice right away.

If that happens it can possibly come back to bite you later on.

Again, it's hard to know exactly what you're seeing without being able to examine the geometry...

- Michael