- key-callbackparameter
Called when a key is pressed or released. Expects a function with the signature (lambda (WINDOW KEY SCANCODE ACTION MODS) ...). WINDOW is the window where the button was pressed, KEY is the name of the key, SCANCODE is the system-specific scancode of the key, ACTION is one of +press+, +release+ or +repeat+, and MODS is a bit field describing the modifier keys that were held down (any of +mod-shift+, +mod-control+, +mod-alt+, or +mod-super+).