These are all related issues that were brought up.

From Bertro:
When ED is set to "None" and you press tab in an empty space "that is still a valid density spot" (but of course invisible since density is set to None) a Note/Purple dot is still created.

This happens even outside of the visible Trim area as long as it is a "valid density spot". I believe not Purple Dots should be "created" on invisible density spot. It is ok to keep pre-existing Purple Dots.

Susume:
When you have trimmed the density and try to add a purple dot, the dot adheres to the non-visible density in the foreground instead of the further-in density you can see and point to. It is rather startling if you are zoomed in and the dot appears suddenly as big as your face.

karstenw: Yep, trim makes placing dots tricky. placing dot on "visible" location would be ideal. if this isn't possible, a "preview" trim slider would make it slightly less tricky.