Removed obsolete test.
Adding (unit) tests.
Simplified and renamed 'position'.

It is now 'show' - the pendant of 'hide'.
Removed the re-positioning logic, as it turned out to be erronous
and has been kind of over-engineered.
Now the caller has the responsibility to hide elements first if
he wants to reposition them.
Not a real change.
First iteration on reactivating copy'n'paste.

Not yet working.