Martin Lafaix has released (7/8/2001) XWorkplace Widgets Library version 0.5.2 for use with XCenter. It contains a REXX button widget, a REXX gauge widget, and more.
OS2world Note: I recommend visiting also http://www.os2bbs.com/os2news/XCenter/ for Xcenter Widgets.
Source: OS/2 ORG