All screenshots are from CocoaGap v0.1 with GAP 4.4.5 and XGAP 4.21.
A GAP session console window:
The subgroup lattice of D8:
Right-click on the Klein 4 subgroup to get an information window:
No environment is complete without a game. XGAP's puzzle example, as seen in CocoaGap:
The preferences window allows changing GAP settings: