This tag is for all questions related to teaching Graphical User Interfaces (GUI) in any environment. The tag can be used for questions of teaching both design and development.
Many programs today have a graphical rather than a textual interface: a GUI. The design and coding principles for such interfaces are a bit different from other (model) programming. Use this tag for all questions related to teaching the design and implementation principles of graphical user interfaces.
The tag (and this site) is not appropriate for specific questions of design (see the Stack Overflow site) or implementation unless those relate to student learning.