1. in removeArea, remove area container from the right parent and do not
remove and destroy helper since helper is child of container (15556e40f4)
2. do not set area and helper position to monitor position value, since their position is relative to the container (that already have the monitor position)
In inactive state, drawing area was over other ui widgets and
prevented drag-and-drop. Now we put the drawing area above windows and
below overviewGroup.
abakkk