FOSS gamedev and creative worlds

map changer needs to be a way that a player can change maps without exiting to menu:
holding down ALT and TAB from keyboard and to show your worlds then if you click on one it will teleport you to the map and what stuff you have in your inventory in your first map and if you change them to have the same stuff in the other map

How would this work with multiplayer servers? Also, Alt+Tab is used by most OSs IIRC. Not all of them will let you override it.