That's handled seamlessly. That happens mostly because of the way their resources are handled. If you lose a rendering context you would need to reload those assets afterward. Because of the way NAS2D handles its rendering context and assets internally, resources don't need to be reloaded when a window is minimized or hidden.
It also helps that there are two versions of 'fullscreen' mode. There's 'fake' fullscreen which is a borderless window that fills the entire desktop resolution and there's the 'real' fullscreen which actually involves a resolution change. In either case the rendering context is maintained and so tabbing out won't cause crashing due to loss of resources.
It is, however, up to the application to respond to window minimize/hide events for things like pausing and generally behaving. I figure that's something that the application developer should be responsible for (comes from the way Windows treats applications and requires that developers build applications that play nice).
