I just tried it in 9.x , found a desk. It says I have to select something before using Add. Maybe you had some customization or I'm looking at a different desk. Is it in-Pro/E browser or external web-browser that you were using?
When I need to work on something I find it much faster to open it in Pro/E. I select Open, type the name, and then go.
Windchill will hunt it down wherever it is, with correct permissions and access, add it to the workspace, and then Pro/E opens it from there. I have to type the entire name because Pro/E won't open a bunch of files at the same time, but it skips having to go to Commonspace, find it, add to a Workspace, then open with Pro/E.