Am 03.07.2012 um 18:04 schrieb luigi scarso:
On Tue, Jul 3, 2012 at 5:27 PM, Alan BRASLAU
wrote: On Tue, 3 Jul 2012 15:48:43 +0200 Hans Hagen
wrote: It's a rather (old) low level boxing macro ...
\start \showboxes \centerbox width 10cm height 3cm {Alan is surprised} \stop
My TeX culture remains, alas, always limited (even if I have the TeXbook on my office bookshelf, indeed \centerbox does not appear in plain TeX). Nothing in the ConTeXt manual, either. Of course, a leisurely browsing of the source code would reveal many such treasures! There is also \vcenter
\starttext xxxxxxxxxxg\ruledvbox{\hsize=5cm\vcenter to 3cm{Alan is surprised}}gxxxxxxxxx \type{\vcenter}\par xxxxxxxxxxg\ruledvbox{\centerbox width5cm height3cm{Alan is surprised}}gxxxxxxxxx \type{\centerbox}\par xxxxxxxxxxg\ruledvbox{\vcenter{\centerbox width5cm height3cm{Alan is surprised}}}gxxxxxxxxx\type{\centerbox+\vcenter}\par \stoptext
(\vcenter is a TeX primitive)
ConTeXt redefines \vcenter because the primitive can only be used in math mode. Wolfgang