library(SJava)
.JavaInit()

 panel <- .JNew("JPanel")
 panel$setLayout(.JNew("BorderLayout"))
 label <- .JNew("JLabel", "(   ,   )")
 comp <- .JNew("JPanel")
 panel$add("North", label)
 panel$add("Center", comp)
 .JNew("GenericFrame", panel, T)
 
 comp$setBackground(.Java("Color", "red"))     

  jdynamicCompile("java.awt.event.MouseMotionListener", "RMouseListener")

  mouseListener <- function(jlabel) {
    x <- 1
    y <- 1        

    mouseMoved <- function(ev) {
     x <<- ev$getX()
     y <<- ev$getY()         
     # print(c(x,y))
     jlabel$setText(paste("(",x,", ",y,")", sep=""))
   }
# If one clicks on the canvas and move the mouse, an error is generated
# because we didn't provide a mouseDragged. So we duplicate the function
# here so that the Java class can find the method.    
   return(list(mouseMoved = mouseMoved,
               mouseDragged = mouseMoved,
               where=function(){c(x,y)}))
 }

 l <- mouseListener(label)    
 r <- foreignReference(l)
 comp$addMouseMotionListener(.JavaConstructor("RMouseListener", r, .convert = FALSE))