Is there a copyright on the user interface (appearance) of programs?

Question

User interface

Hello. I have a development: xdsoft.net/jodit/ - WYSIWYG editor.
The editor was born after searching for a free alternative. Of all the proposed, not a single editor suited me, and paid analogues are very expensive. That's why I wrote my own editor. All the code from was written from scratch, but I borrowed the appearance and functionality from several paid editors, including www.froala.com/wysiwyg-editor
Outwardly, a number of elements are similar, but made differently, but inside the editor should be radically different, since I did not see their source code, but I wrote my own from scratch.
Another similarity is that both they and I use free Font Awesome icons .
Today they wrote to me from their company, and within 7 days, in an ultimatum form, they politely asked me to remove the editor from the site, to remove any mention of him on the network. Otherwise, he threatens to take action in court.
The question is: should I do what they ask, what threatens me with the opposite, or maybe I should contact a lawyer?
UPD dated 10/27/2016 For those
who are interested: according to the advice below, I slightly changed the design (quite a bit), colors and frames. Somewhere swapped elements. A week has passed, another letter from them
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- Although you ignored us, we know that you read the letter, since you began to change the design. We are good, and we still want to agree on a good thing, remove your development from all places within a week and then we will not turn to lawyers.

Answer 1

I looked at their website at the link provided. There is no information about the company or about an individual - there is no official information at all, not even a phone number. Most likely it is either one person or a small team from Romania earning without paying taxes. Payment methods - only PayPal and credit cards (which accepts the same PayPal) also testify to this.
Therefore, there is nothing to be afraid of here at all, you can safely hammer their email into the black list of the spam filter and live in peace.
It’s better to never answer such emails at all, in which case you can say that you didn’t receive anything at all, then you can always change the protection tactics in which case.

Answer 2

You need to check their rights and, preferably, protect yours.
I think that with a probability of 99% - they scare.

Answer 3

What does copyright in software have to do with it?
They, according to your statement, do not claim that you stole the code from them.
They rest on the similarity of design.
Well, make "thing doesn't look like a bomb" like it's a problem...

Answer 4

If they do not have a representative office in Russia, put it on all their letters. The decisions of the American (Romanian) courts do not care. The maximum they will be able to somehow get what falls into their jurisdiction, a hoster, etc.

Answer 5

I don’t know how it is in Romania, but in Russia the author’s monopoly on the visual appearance of programs still exists.
What keeps the proprietors from getting bogged down in lawsuits against each other¹ and saves the free software authors from getting scolded about their appearance is that it doesn't cross the threshold of originality, stemming from its purely functional (as opposed to aesthetic) purpose. In simple terms, if two authors undertake to independently draw gui programs to solve the same problem, then they should end up with basically the same thing.
The only thing that can be concluded from here, without actually seeing what your comrades in the proprietorship production shop ran into you with, is thathonestly admitting that you borrowed something from them was not the most reasonable decision in your situation .
As for “contacting a lawyer”, this is always harmless, and here it is also undoubtedly useful in that he will somehow get you to provide him with the text of the claim, while you simply ignore similar wishes here again and again.
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¹ Although sometimes it does not help, a textbook example is Apple vs. Microsoft , but this was in the early days of gui.

Answer 6

Hello. And what tutorials, articles, books did you use to create such an editor? Please give links, it is interesting to read and do it yourself)

Answer 7

Who cares: following the advice above, I slightly changed the design (quite a bit), colors and frames. Somewhere swapped elements. A week has passed from them again a letter
- Although you ignored us, we know that you read the letter, as you began to change the design. We are good, and we still want to agree on a good thing, remove your development from all places within a week and then we will not turn to lawyers.