Merge changes I0b8b2ee3,Ib71f8f77,Ica481295,Iaf871389,Iab9a445d

* changes:
  Restrict drag in gesture to recents button
  Fix flickering while dismissing docked stack
  More optimization while dragging docked divider
  Don't relayout when windows move during resize
  Optimize window relayouts when dragging divider