[FIX] popup: Restore lost "background" mode as used by the img plugin with thumb=mouseover or mousesticky.
Some extra CSS changes required to get both cases working: with a width supplied and without (also grouped all cluetip css together)

git-svn-id: file:///var/local/code.tiki.org/tikisvn/branches/11.x@47742 b456876b-0849-0410-b77d-98878d47e9d5