I wrote this small program to test the use of a a gui in a separate JFrame. It works fine with the radiobuttons, sliders, and checkboxes, but when I tried to add a button for saving the sketch to an image, I got a "cannot call invokeAndWait from the event dispatcher thread" error. This must be some sort of conflict between processing and swing's event handling?

[How could I get around this - use a JFileChooser instead? I would then have to get the text from the File object. to use in the processing loadImage method... myFile.getName(), maybe. I will try this and see if it works.] - edit - this is for the loading file issue, not saving -but has same problem.

Any other suggestions welcome

Code:

import javax.swing.JPanel;
import javax.swing.JFrame;
import javax.swing.JCheckBox;
import javax.swing.JRadioButton;
import javax.swing.ButtonGroup;
import javax.swing.JButton;
import javax.swing.JLabel;
import javax.swing.JSlider;
import javax.swing.event.*;
import java.awt.*;
import java.awt.event.*;

JFrame frame;
JPanel panel;
JLabel label;
JSlider Slider;
JButton button;
JRadioButton Red, Blue, Green;
ButtonGroup Group;
JCheckBox Smooth, big;
int mode =1; //1=small, 2=big;
int angle;


void setup()
{
  size(400, 400);
  rectMode(CENTER);
  label = new JLabel("Drawing Options");
  frame= new JFrame("Drawing");
  panel = new JPanel();
  button= new JButton("Save");
  Smooth = new JCheckBox("smooth");
  big= new JCheckBox("big");
  Red = new JRadioButton("Red", true);
  Green = new JRadioButton("Green");
  Blue= new JRadioButton("Blue");
  Group = new ButtonGroup();
  Group.add(Red);
  Group.add(Blue);
  Group.add(Green);
  guilistener listener = new guilistener();
  Smooth.addItemListener(listener);
  big.addItemListener(listener);
  Green.addActionListener(listener);
  Red.addActionListener(listener);
  Blue.addActionListener(listener);
  button.addActionListener(listener);
  Slider = new JSlider (JSlider.HORIZONTAL, 0, 360, 0);
  Slider.setMajorTickSpacing (50);
  Slider.setMinorTickSpacing (10);
  Slider.setPaintTicks (true);
  Slider.setPaintLabels (true);
  Slider.addChangeListener(listener);
  panel.add(label);
  panel.add(Smooth);
  panel.add(big);
  panel.add(Red);
  panel.add(Blue);
  panel.add(Green);
  panel.add(Slider);
  panel.add(button);
  frame.getContentPane().add(panel);
  frame.pack();
  frame.setVisible(true);
  
  noStroke();
  background(255); 
  fill(255,0,0);
  
}

void draw()
{
  background(255);
  pushMatrix();
  translate(width/2, height/2);
  rotate(radians(angle));
  if (mode==1)
  rect(0, 0 ,100, 100);
  else rect(0,0,200, 200);
  popMatrix();
}


class guilistener implements ItemListener, ChangeListener, ActionListener
{
  public void itemStateChanged(ItemEvent event) // for checkboxes
  {
    if(Smooth.isSelected()) smooth();
    else noSmooth();
    
    if (big.isSelected()) mode=2;
    else mode=1;
  }
   public void stateChanged (ChangeEvent event) //for sliders
   {
	   angle = Slider.getValue();
   }
  
   public void actionPerformed(ActionEvent event) //for radio buttons
   {
	  Object source = event.getSource();
	  
	    if (source==Green) fill(0,255,0);
	    else if (source==Red) fill(255,0,0);
	    else if (source==Blue) fill(0,0,255);
	    else if(source==button)
	    {
		String savepath=selectOutput();
		if(savepath!=null) save(savepath);
	    }
   }
  
}