This is the base class for some classes that monitor the mouse and keyboard input and perform some action due to their state.
It collects together some common interface; in particular, the
require_button()and related methods.
Removes all requirements on buttons set by an earlier call to
Removes any requirement on the indicated button set by an earlier call to
Indicates that the indicated button must be in the required state (either up or down) in order for this particular
MouseInterfaceNodeto do anything. For instance, this may be called to make a Trackball object respect mouse input only when the control key is held down.