@Martin - It is a two step process to add a widget.. First you must select "Create a Widget" on the popup menu - and select the widget you want to "create" from the list. Then you have to add the widget using the "Add Widget to Tray" option on the popup menu. For versions 1.0.13 and 1.0.12 the "Add Widget to Tray" option is missing from the popup menu. The first attachment (popupmen.jpg) shows the popup menu for v 1.0.13 (and for v 1.0.12)
@Andreas - The "Add Widget to Tray" option is clearly missing from the popup menu. You can see two lines in the menu where the option is supposed to be - but no option. If you compare the first attachment with the second you can see where the option is supposed to appear in the menu.
It does appear that "Create a Widget" has been added to more menus (or more contexts where it shows up on the menu) which is very nice. That appears to have happened, as you point out, after version 11. Previously it was a pain to try and point to the right area on the xCenter to get a menu with that option.
@Me (And Doug B.) Yes there is a difference between xWorkplace and the xWorkplace in AOS. Thanks Doug B. (and others) for pointing out where that package is located. I installed \CID\SERVER\ARCAPKG\ANXWP_EN.WPI from the AOS v 5.0.6 distribution and got the Removable Media widget (already installed) on xCenter.
But the AOS version of xWorkPlace is not the same as the "full" version of xWorkPlace - and possibly not the same as xWorkPlace lite (although I didn't install xwps lite to compare). The AOS version is missing turbo folders with the different way of associating files to program objects - for one example. I am not saying the AOS version is bad - it isn't. It is just missing some features that I want.
The AOS version of xWorkPlace reports being version 1.0.13.1 - so it is a later version than what is available as "full" xWorkPlace.
The way I fixed my problem was:
1) deinstall xwps 13
2) install aos xwps from the distro (I had to uninstall xwps v 1.0.13) to get this to work
3) copy the RemMedia.* and RemM_*.* stuff from c:\sys\apps\xwpd\plugins\xcenter to a temporary location
4) deinstall aos xwps
5) install xwps version 1.0.11. The Add Widget option is missing from the popup menu of v 1.0.12 also)
6) copy the removable media files from the temporary directory back to the xcenter directory.
7) install the removable media widget: Create Widget and then Add Widget - making sure to close xCenter before each step

install xwps v 1.0.13
Whew
The conclusion is at this point in time there is no easy way for AOS customers who want to run the lastest version of full xWorkPlace to get the removable media widget installed.
Thanks everyone for your help.