defaults bugs n fixes

[Joerg Fischer]

Tony Balinski wrote:

> Back to .dtx, though, it doesn't sound as if calling it a LaTeX file is
> much of an issue really, since the choice is between unuseful highlighting
> (but which gives access to LaTeX macros)

Yes there are latex macros that are useful in dtx, too, for example
running latex over the file and calling xdvi to preview the ouput.  
But macros for editing task will need some modifications to respect
the % at the start of each line.  Moreover, there are macros for dtx
that don't make sense in latex mode, and indentation, wrapping and
auto new line also work differently because of the %'s. 

So, although we spoke only about highlighting so far, dtx requires
its own language mode really.

Cheers,
Jörg