Longpressing in landscape correctly starts selection mode.

Two issues here:
1. selection mode was stopped when extracted mode started,
thus loosing the selection.
2. starting selection mode shows a transient action bar which
is then hidden when extracted mode starts. Detect this case
and do not start selection mode, which will start in extracted
mode. This also solves 1.

Change-Id: I61d6e8d2071e9d3b1a136915b685962bbc093bd0