This is still available via ActivePage.CenterDrawing in VBA, but prior to 2010 Ribbon garbage it had also been available via one of the command drop downs. Even on MS online site searching for ActivePage.CenterDrawing shows no results! but then, why would I expect info there...
Would you believe it's not on the ribbon at all!
You'll have to add it yourself. File -> Options - > Cutomize Ribbon
Did you know that the secret project codename for the Ribbon UI was Sabotage? True.
Really?!? I thought it was...Doh!
As in Doh! did we do that? :o ::) >:(
The Ribbon is NOT one of my favorite topics!!! But at least I know what MS stands for...moronic stupidity!
Wapperdude
Though it is too late to say,
"Find Visio Command Addin" by Nikolay is really useful to find the lost command .
http://unmanagedvisio.com/products/find-visio-command-addin/