do not let buttons cover content

1, button covers content issue
2, stop timers after dismissing the bubble
3, start quitTimer at the beginning

tower: https://tower.im/projects/8f19f0bf0e754f0b82ef2c24bc230973/todos/ab64a4ac2c914c7e9dbea25257a8cb9d/

Change-Id: I422e6d55332b5947ec06e9198d0ae1a8b5a2a4fc