D15023: [server] Add selectionChanged signal

[Roman Gilg]

romangg added a dependent revision: D15421: [server] Add surface data proxy 
mechanism.

REPOSITORY
  R127 KWayland

REVISION DETAIL
  https://phabricator.kde.org/D15023

To: romangg, #kwin
Cc: kde-frameworks-devel, michaelh, ngraham, bruns