Holding a key and get options for punctuation

I use Ubuntu in English but I often type Dutch, Afrikaans or Frisian on my keyboard. The problem is now that I do not remember all those shortcuts of [alt + ...] to get the sign on the [e, a, u, o or i]. Android uses a very smart solution for that, by holding the keyboard key longer, it won't show thousands of e's but will provide options with é, ë and so on.

Good idea for Ubuntu maybe? We have to find out if it is patented.