Opening GUIs by Command
The /openguiscreen command opens Vanilla, mod, and Custom GUIs. It can target other players when FancyMenu is installed on the server and their clients.
To open a GUI, use /openguiscreen <screen_identifier> [<target_players>].
Replace <screen_identifier> with the exact, case-sensitive identifier of the Custom GUI or Vanilla/mod screen.
To find an identifier, open the target screen and enable the debug overlay with CTRL + ALT + D. Select the identifier on its first line to copy it. See Screen Identifiers.
Omit [<target_players>] to open the GUI for yourself, or use a player name or selector such as @a to open it for one or more players. Supplying the target argument requires permission level 2 (Game Master / OP level 2), even if it names yourself, and every target player needs FancyMenu installed on their client.
Not every mod screen can be created directly. FancyMenu shows an error when a target screen is unsupported. In a local layout, use Mimic Vanilla/Mod Button on the widget that normally opens it.
Closing GUIs by Command
In the rare case you need it, /closeguiscreen [<target_players>] closes the current screen. It affects you when the target is omitted; supplying the target argument requires permission level 2.