// we fork a new layout process, compute the value and then come
// back with the result.
final Object value = LayoutControllerUtil.performPrecompute
(i, new ElementPrecomputeKey(element),
this, getFlowController());
slots[i] = new PrecomputedExpressionSlot(expression.getName(), value,
expression.isPreserve());
}
else
{
// thats a bit easier; we dont have to do anything special ..