Motion Elements exceeding timeline

I have the following problem:

I wanted to trim the duration of a behaviour in Motion but couldn't, as the element exceeded the timeline and therefore could not be grabbed by its handles. This is the case for other elements as well. I am zoomed out as far as possible and can not scroll on the timeline, still these elements exceed the total length of the timeline by a factor of 5 or so.

In the picture you can see several elements. The middle two are trimmable as their ends are in frame, the others are not.