Currently, a mask is applied underneath the screen so any object in the screen is rendered on top of the mask. Moreover, it doesn't allow to use layouts.
It would be useful if to have layouts in masks and to have a new mask class that overlays the screen.
In my current project, we are managing the user access to certain screens by applying a big label that covers most of the screen. This label becomes invisible if the user security profile (~db) fulfils certain criteria, allowing the user to see and interact with the objects underneath the big label. At the moment we have to place the labels manually in each screen, and every time we want to modify the screen we need to move the big label around. Having this new mask class that overlays the screen could allow us to implement the same strategy in a much easier way.
I am sure other developers will find other uses to this new mask class.