A singleton for managing [TextServer] implementations. [TextServerManager] is the API backend for loading, enumerating, and switching [TextServer]s. [b]Note:[/b] Switching text server at runtime is possible, but will invalidate all fonts and text buffers. Make sure to unload all controls, fonts, and themes before doing so. Registers a [TextServer] interface. Finds an interface by its [param name]. Returns the interface registered at a given index. Returns the number of interfaces currently registered. Returns a list of available interfaces, with the index and name of each interface. Returns the primary [TextServer] interface currently in use. Removes an interface. All fonts and shaped text caches should be freed before removing an interface. Sets the primary [TextServer] interface. Emitted when a new interface has been added. Emitted when an interface is removed.