improve real floating views screen edge activation

• when the user hovers the screen edge there is a chance that

screenedgeghostwindow has become underneath the view. In such
case when the real floating window slides in the screenghostwindow
becomes unhovered faulty and it is destroyed afterwards. It is
much better if the screenedgeghostwindow in such case remains shown
until the mouse is not contained neither in the view or the screen
ghost window

• expose screen edge ghost window thickness