* Window icons are set in vcl/unx/source/window/salframe.cxx.  Grep
  for XSetWMHints there, and also for SelectAppIconPixmap.

* SelectAppIconPixmap() lives in vcl/unx/source/app/soicon.cxx.  It
  generates a function name and dlsym()s the result (!), calls the
  resulting function, and gets an inline XPM from it.

* Right now it only uses a pixmap/mask pair; we should add support for
  _NET_WM_ICON:

  - How do we fetch an RGB icon (class Bitmap) at that point based on
    the nIcon argument to SalFrame::setIcon()?
