This is a start at the "Active Appliction Item" component of the
shell design. Currently we just show the currently focused
application. When launching a new application, we show that as well.
The implementation here is not complete; basically when launching
we de-focus the active one, and the application well shows the
most recent startup sequence.
This kind of fails in the case of multiple sequences, and we
also don't correctly de-focus the current window in other
launch paths.
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