Add a 1px black line to waterfall when switching frequencies?

[schweini]

Great program!

I have a small nitpick, though: every single time I change frequencies, I find the waterfall slightly confusing, because it seamlessly just continues.

Something - anything - to seperate the waterfall from before and after the frquency change would make this way more intuituve, at least for me. Maybe some option of "add a 1px black line to waterfall when changing frequency"?