It's not a bad model, but I'll toss in another for consideration. Motif
handles 2-dimensional layout (in its more interesting widgets) by
letting you specify the location of objects *in relation to each other*.
That is, you can say, "Put this thing in the upper left, this one next
to it, this below it, and this to the right of the one below it,
stretching all the way to the right edge." I'm not sure how well
that maps to 3-space (where, among other things, stretching images
to fill the pane isn't nearly as important), but something analogous
to this would be worth at least considering...
Random Quote du Jour:
"... panic can be a great breeder of massive inspirations."
-- Lady GraziaGeralda Louisa de Navarra