Found several nasty problems with template screens:

1. When a template is linked to a template, the screens inherited from the parent template are not displayed in the configuration. They should be displayed as readonly items.
2. It is possible to create a screen on a child template with the same name as a screen from a parent template. It will override the screen on any descendant templates or hosts.
3. When creating a screen on a parent template with the same name as an existing screen on a child template, the child screen is not linked to the parent screen.
4. When unlinking a template, the template screens are removed from the child hosts or templates, although we were not supposed to "clear" them.