return dirty;
}
PlotCanvas(Plot plot) {
this.plot = plot;
painter = new PlotPainter(plot);
setOpaque(true);
setBackground(java.awt.Color.WHITE);
setCursor(java.awt.Cursor.getPredefinedCursor(java.awt.Cursor.CROSSHAIR_CURSOR));
addMouseListener(mouseListener);
addMouseMotionListener(mouseMotionListener);