TODO additions

[Dave Love]

I'd like to see these added to etc/TODO.  The last three are
maintenance problems that have bitten me again recently; I know rms
thinks they're not a problem, but they've all bitten me again recently
and have done often in the past.  The rest are mostly of particular
interest for W3, but are more generally applicable.

* Provide a means to display a background image in a window [miles
  started on this?] and extract image-relative coordinates from mouse
  clicks on images.  (Both needed for W3.)  Also useful for W3 and Gnus:
  allow scrolling images properly.

* Convert the XPM bitmaps to PPM, replace the PBMs with them and scrap
  the XPMs so that the colour versions work generally.  (Requires care
  with the colour used for the transparent regions.)

* Allow unknown image types to be rendered via an external program
  converting them to, say, PBM (in the same way as PostScript?).

* Allow displaying an X window from an external program in a buffer,
  e.g. to render graphics from Java applets.  [gerd and/or wmperry
  thought this was feasible.]

* Allow images (not just text) in the margin to be mouse-sensitive.
  (Requires recursing through display properties).  Provide some way
  to simulate mouse-clicks on marginal text without a mouse.

* Implement Lisp functions to determine properly whether a character
  is displayable (particularly needed in XFree 4, sigh).  Use it to
  define useful glyphs that may be displayed as images or unicodes
  (with ASCIIfied fallback via latin1-disp).  Examples include
  box-drawing graphics in Custom buffers, W3 rules and tables, and
  tree displays generally, mode-line mail indicator.  [See work done
  already for Emacs 22 and consult fx.]

* Do something to make rms happy with fx's dynamic loading, and use it
  to implement things like auto-loaded buffer parsers and database
  access in cases which need more than Lisp.

* Extend ps-print to deal with multiple font sizes, images, and extra
  encodings.

* Provide portable undumping using mmap (per gerd design).  [unexec
  _is_ a major headache.]

* Use automake and use autoconf fully, preferably avoiding src/{m,s}
  entirely.  [Maintaining the build process _is_ a major problem.]

* Replace gmalloc.c with the modified Doug Lea code from the current
  GNU libc so that the special mmapping of buffers can be removed  --
  that apparently loses under Solaris, at least.