public synchronized void gotopreviousmain ()
	// goto previous game tree
	{
		if (CurrentTree == 0) return;
		State = 1;
		getinformation();
		T.top().setaction("AP", "Jago:" + GF.version(), true);
		T.top().setaction("SZ", "" + S, true);
		T.top().setaction("GM", "1", true);
		T.top()
			.setaction("FF", GF.getParameter("puresgf", false)?"4":"1", true);
		CurrentTree--;
		T = (SGFTree)Trees.elementAt(CurrentTree);
		resettree();
		setnode();
		showinformation();
		copy();
	}