Success Criterion 2.1.1 (Keyboard) states that all functionality provided by the content should be operable using the keyboard, "except where the underlying function requires input that depends on the path of the user's movement and not just the endpoints". The AAA version of this is Success Criterion 2.1.3 (Keyboard: No Exception), which precludes content requiring the quoted exception from reaching AAA conformance.
This example should fire warnings relating to the usage of mouse-specific events for performing functionality. Authors should check that the functionality provided by these events are also provided by keyboard events in some fashion, or consider using device-neutral events. The messages provide suggested alternative events, but these do not have to be followed exactly as long as the functionality is available.
These warnings will appear even if there are the equivalent suggested keyboard events available, because the author should check that the included keyboard events provide all of the functionality of the mouse events.
(The "*" in the message is replaced by the name of the mouse event: MouseDown, MouseUp, MouseMove, MouseOver, MouseOut, or DblClick.)