Return the actor (if any) that the current mouse behaviour is related to.
If the mouse was clicked or pressed the actor it was clicked on will be
returned. If the mouse was dragged or a drag ended, the actor where the
drag started will be returned. If the mouse was moved, it will return the
actor that the mouse is currently over.
Actor that the current mouse behaviour relates to, or null if
there is no actor related to current behaviour.
public int getButton()
The number of the pressed or clicked button (if any).
The button number. Usually 1 is the left button, 2 is the middle
button and 3 is the right button.
public int getClickCount()
Return the number of mouse clicks associated with this mouse event.