* The list of candidates now includes unknown variants. When an unknown
variant is selected, the unknown game dialog is shown.
* On the unknown game dialog, users are given the choice to add the game
when that is possible, or to cancel.
The goal of those changes is to make the unknown game dialog less
confusing for users, especially when both known and unknown games
variants are found.
The code is still disabled, but it is now in a working state and
can be tested by removing the #if 0 and changing the URL to a test
server with a redirect rule.
This should also fix this for other instances of ScrollContainer, though
the dialogs / widgets may require the same change.
This fixes bug Trac #10741.
