void button_load_clicked()
	{
		FileDialog dialog = new FileDialog(new Frame(),"Load",FileDialog.LOAD);
		dialog.setVisible(true);
		String filename = dialog.getDirectory() + dialog.getFile();
		if (filename == null) return;
		clear_all();
		try {
			BufferedReader fp = new BufferedReader(new FileReader(filename));
			String line;
			while((line = fp.readLine()) != null)
			{
				StringTokenizer st = new StringTokenizer(line," \t\n\r\f:");
				if(st.countTokens() == 5)
				{
					byte value = (byte)atoi(st.nextToken());
					st.nextToken();
					double x = atof(st.nextToken());
					st.nextToken();
					double y = atof(st.nextToken());
					point_list.addElement(new point(x,y,value));
				}
				else if(st.countTokens() == 3)
				{
					double y = atof(st.nextToken());
					st.nextToken();
					double x = atof(st.nextToken());
					point_list.addElement(new point(x,y,current_value));
				}else
					break;
			}
			fp.close();
		} catch (IOException e) { System.err.print(e); }
		draw_all_points();
	}