Emacs/X-Symbol things to do:
 * when using the invisible text property, "reveal-invisible" doesn't work
 * isearch + grid doesn't work
 * image support needs clear-cache
 * temporary images don't work
 * ispell: Ispell misalignment
 * info: when displaying, area uses 2 lines of vertical space (is not
   necessary), can also be seen if quail displays selection option (1.C1 2.C2)
 * quail: MAXIMUM-SHORTEST is not enough if we define <-> and -+ and type <-+
 * possible to set a buffer-local default face?

X-Symbol things to do:
 * grid: tab width - 1
 * input method QUAIL
