How difficult will it be to program a website editor program like Dreamweaver, Frontpage, Nvu, Coffee Cup, or Kompozer with the same amount or more features by using a widely popular codding language like Java, C++, C, C#, etc from scratch?
Which would be the best programming language to code a WYSIWYG website editor with?
Is it even worth it to code your own website builder from scratch to market and sell for a cheaper price then Dreamweaver or Frontpage which dominate most of the WYSIWYG website design market?
A WYSIWYG editor contains various powerful components such as multiple render engines, a full ftp/publishing client, as well as local server and php support. Which... would take a room of people to code.
A common saying of hackers is, "Don't reinvent the wheel." Meaning if you'd like a better editor or any other type of software, don't build a new one. There is probably a good open source editor out there that you could help contribute to.
However, to reach that skill in programming takes years and you should concentrate on building up your skills with simple projects first.