> Just two examples:
> Friendly means that user should not be puzzled by UI , like what does
> that red rectangle means.
> Drawing a semitransparent 'changed... [v][x]' in the text morph corner
> is what i calling friendly.

I would call that not only friendly, but also drop-dead gorgeous.  The
translucency would be necessary not just to not interfere with the
main text of the code (which, if using Indented Control Flow, probably
wouldn't extend into the.. upper-right? corner anyway).  No, the other
reason is that it's a "meta" UI-message from the TextEditor is not
part of the users "concrete" content..