GEM/4

From GEMWiki

FreeGEM Desktop running under GEM/4 (invisibly, as it looks just like GEM 3)

Artline 2 running under GEM/4

GEM/4 is an AES and VDI bundled with Artline 2; it can be made to run other applications. However, the AES seems to have a tendency to cause redraw glitches when dialog boxes go away. It also looks very nearly identical to GEM 3 for most practical purposes.