Run this code.

package bug;

import javafx.scene.control.Button;
import javafx.application.Application;
import javafx.event.Event;
import javafx.event.EventHandler;
import javafx.scene.Scene;
import javafx.scene.control.ColorPicker;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

/**
 *
 * @author fx
 */
public class Bug extends Application {
private static int i=1;
    @Override
    public void start(Stage stage) throws Exception {
        VBox root = new VBox();
        Button cp = new Button();
        cp.setOnMouseMoved(new EventHandler(){

            @Override
            public void handle(Event t) {
                System.out.println("Move" + i++);
            }
        });
        root.getChildren().add(cp);
        Scene scene = new Scene(root,200,200);
        stage.setScene(scene);
        stage.show();
    }
    public static void main(String[] args) {
        launch(Bug.class,null);
    }
}

Then click on button and wait. You will see on console, that there will be MouseMove Event with some period.