Fix switching of active window.

When getting a surface leave/surface enter pair, the enter event was lost.
It could be seen when opening a popup menu. This patch uses a wl_callback
to activate the right window.

Change-Id: Ibd35fcaa0d43f4723dd7aeff71264d6145411a08
Reviewed-by: Andy Nichols <andy.nichols@digia.com>
Fix warning unused

Change-Id: Iaab48cb9a9b6675579f00dd2a5eb038c5e94904a
Reviewed-by: Jan Arne Petersen <jan.petersen@kdab.com>
Reviewed-by: Paul Olav Tvete <paul.tvete@digia.com>
Update error text to match required Wayland version

The required Wayland version was updated to 1.1, but the top-level error
message was not updated to reflect this.

Change-Id: Ifc1c7552a4a38986685c214e24241704fd774e11
Reviewed-by: Jan Arne Petersen <jan.petersen@kdab.com>
Reviewed-by: Paul Olav Tvete <paul.tvete@digia.com>