Would like to see someone make their own WYSIWYG editor.
It's an amazing fun thing to do, but I probaby wouldn't wan't to do it again now. This thing didn't handle unicode (I had never heard of it), barely handled spell checking and didn't handle bi-directional input.
Text (1 byte per char) was stored in a big array on the heap. Styles were also an array (again on the heap) of fixed length structs. Font information, in the form of fixed-point width tables, was gathered from system calls and cached.
It did actually support inline pictures though, which was pretty challenging.
Writing an editor is a hugely fun project. Highly recommended.