This reverts commit 4aa0ee61.

When the time comes to merge dev into master (for real), the
following may be useful:
https://metlos.wordpress.com/2012/01/13/
git-merging-after-a-revert/

Navigation palette: thumbnails isn't refeshed after application added to the page

UBToolWidget API has been deactivated, there is certainly a lot of bugs, code is ugly.
Remember to fix commented sections (forgotten which ones).

This is not functional.