BOX-LAYOUT-MIXIN     - only consider enabled children     - consider children in reverse order
BOX-LAYOUT-MIXIN
    - only consider enabled children
    - consider children in reverse order

ALLOCATE-SPACE viewport-pane
    - fixed <200202272318.PAA24948@saturn.mikemac.com>
      by using LAYOUT-CHILD now, that is extrema of the child's space
      requirement are taken into account. Still not sure if this is
      really the right thing to do.

quek/mcclim,informatimago/mcclim,quek/mcclim,informatimago/mcclim