greeter-theme:update rain theme
greeter-theme:update sky theme
greeter-theme:update sky --use iframe
greeter lock:theme_iframe zindex = 1 and lock greeter element zindex = 10
res/app:dock:: try to fix dnd problem.

dnd leads to region problem.

reason:
1. the dock state is hovered, the region cannot be updated.
2. maybe others...