Spawn a character in the menu. To open the menu, click the blue square. Once you opened the menu, click the left and right arrows to browse through characters. The characters will walk around. You can also drag them, but don't run them into the wall. if you do they will die [asriel dreemurr, fancy frisk aka donald frisk and gaster can't get hurt] To exit menu then click it again. Also, fancy frisk now actually appears after 60 seconds.
Credit to DaSwagGamer77 and FloweyTheFlower42.