Command cancelCmd = new Command("Cancel", Command.CANCEL, 0);
Command stopCmd = new Command("Stop", Command.STOP, 0);
// we add the commands in reverse order so that we are
// sure the button layer is sorting it correctly
canvas.addCommand(stopCmd);
canvas.addCommand(cancelCmd);
canvas.addCommand(exitCmd);
canvas.addCommand(backCmd);
checkLeftBtn(canvas, backCmd);
}