[Feature request] buffer-local default font, tab-width in pixels

[Wedler, Christoph]

It would be excellent if users could specify the default font per
buffer, not only per frame.  E.g., I like to have fixed-width fonts for
programming languages, but var-width fonts in LaTeX, HTML texts[1], and
I dont' know why this should force me to use different frames for them.

Another advantage would be that the feature request below becomes less
important.

For fine-tuned tabs, it would be excellent if the tab-width could be
specified in pixels, not just chars (in the default font).

- Christoph

[1] yes, I know, these are kind of programming languages as well