app/res:dock:: try to fix preview window problem.

sometimes, when a window is created or is destroyed, preview window is popped
up.

maybe reason:
moveHoverInfo is triggered.
sometimes preview window or tooltip is shown, however, a window is created or
is destroyed, the preview window or tooltip should be changed to the correct
one.

Change-Id: I2e66775f4bd32ddc64500cbb2ec6eff0e909d5d3