am 9922539f: Merge "Preload only visible thumbnails and task icons. (Bug 17672056, Bug 18291345)" into lmp-mr1-dev automerge: 147de3a automerge: 6a601c9

* commit '9922539facdc52124f9329969c74dcc7b39c8161':
  Preload only visible thumbnails and task icons. (Bug 17672056, Bug 18291345)