Multiple transparent JPanels paint problem (smearing strings)

Question

I created full screen JWindow application.
I created three panels:
MainPanel - non transparent
PPIPanel - transparent
GlassPanel - transparent.
All three panel and JWindow has the same bounds. Then I added PPIPanel and GlassPanel to MainPanel and then I added MainPanel to JWindow.
MainPanel.add(PPIPanel);
MainPanel.add(GlassPanel);
JWindow.getContentPane().add(MainPanel);
Whole application displays Air Traffic Situation comming from RADAR. MainPanel is a black background with airways, PPIPanel displays aircrafts and GlassPanel is MouseEvent listener for ZOOM, CENTER and other mouse operations.
The painting code is always placed in paint(Graphics g) metod of each component. All aircraft are painted on the transparent PPIPanel with small dot fillOval() and two BOLD strings g.drawString("Aircraft")descibing aircraft.
paint(Graphics g) {
g.setColor(Color.GREEN);
g.setFont(bold font);
iterate Collection of aicrafts {
g.fillOval(x,y,4,4);
g.drawString(x+3,y+3,"Aircraft xxx");
g.drawString(x+3,y+18,"Flight level");
The situation is changing every 4 seconds and every 4 seconds special Thread calls repaint() method on PPIPanel to referesh the situation.
The main problem is garbage remaining after refresh. Some aircrafts has smeared label after repaint ( probably because multiple transparent panels).
What are your proposals to solve the problem. I'm just a java begginer so I need clear explenation (i.e. code example).

Answer 1

just to make it clear
paint(Graphics g) {
super.paint(g)
g.setColor(Color.GREEN);
g.setFont(bold font);
iterate Collection of aicrafts {
g.fillOval(x,y,4,4);
g.drawString(x+3,y+3,"Aircraft xxx");
g.drawString(x+3,y+18,"Flight level");
or
paintComponent(Graphics g) {
g.setColor(Color.GREEN);
g.setFont(bold font);
iterate Collection of aicrafts {
g.fillOval(x,y,4,4);
g.drawString(x+3,y+3,"Aircraft xxx");
g.drawString(x+3,y+18,"Flight level");
should work..
Cheers
Mike