Created attachment 70604 [details]
No UI opens when the button is clicked.
In the Paths area of Options if you want to change the location of "My Documents" you can normally click on the EDIT button and it gives you dialog to pick the new directory. Clicking on this button yields no UI. No errors are reported on the command line.
Attaching shot of the problematic dialog button.
Tested on master compiled around 2012-11-25
This has been fixed with <http://cgit.freedesktop.org/libreoffice/core/commit/?id=cc360f0a483e7c68ece7a30424f204d660d74b1c> "fdo#46808: Missing adaptions to XFolderPicker2." The fix should show up in new 4.0 builds soon.
Fixed in Version 220.127.116.11.alpha1+ (Build ID: 704fdf2b23d0e0480f29e0e56f631c2835eed02)