Word should enable a new submenu in the "Format" menu called "Center in
form", which would contain two items called "Vertical" and "Horizontal".  
These buttons would center the selected autoshape(s) in the middle of the
page when the View / Print Layout menu is selected.  It also could be set to
always be centered, so in web layout mode the autoshape would be centered in
whatever the web page width is.

This would be helpful, for example, if you want to put an autoshape line
down the middle of the page or across the page.  It could be centered
perfectly and automatically with this tool.

(microsoft- this is the same concept as centering a control on an object in
visual basic's ide)