HelloWorldWindow.java

import com.intellij.openapi.project.Project;
import com.intellij.openapi.wm.ToolWindow;
import com.intellij.openapi.wm.ToolWindowFactory;

import javax.swing.*;

/**
 * Created by androhi on 15/09/15.
 */
public class HelloWorldWindow implements ToolWindowFactory {

    @Override
    public void createToolWindowContent(Project project, ToolWindow toolWindow) {
        JComponent parent = toolWindow.getComponent();
        JPanel panel = new JPanel();
        JLabel label = new JLabel("Hello World!");
        panel.add(label);
        parent.add(panel);
    }
}