Manager for the font and complex text layout servers. [TextServerManager] is the API backend for loading, enumeration and switching [TextServer]s. Note: 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 an [TextServer] interface. Finds an interface by its name. Returns the interface registered at a given index. Returns the number of interfaces currently registered. Returns a list of available interfaces the index and name of each interface. Returns the primary [TextServer] interface currently in use. Removes interface. All fonts and shaped text caches should be freed before removing interface. Sets the primary [TextServer] interface. Emitted when a new interface has been added. Emitted when an interface is removed.