DESCRIPTION:

Set the flags on an event handler.
Event handlers can be apllied on different scopes:
- [G]lobal, if the event should fire for all views and renderers
- [R]enderer, if it should only fire for views with a specific
  renderer
- [V]iew, if it should fire only for a specific view.
Type tells which kind of event to react to:
- [m]ouse events. See REGISTER_MOUSE.
- [k]ey events. See REGISTER_KEY.
- [c]ommand events. See REGISTER_COMMAND.