public void setDefaultCommandHistory() {
        // Insert default tools into command history for convenience.
        File file = new File(".");
        File files[] = file.listFiles();
        for (int i = 0; i < files.length; ++i) {
            String name = files[i].getName();
            if (name.endsWith(".java")) {
                name = name.substring(0, name.length() - 5);
                try {
                    Class c = Class.forName("filters." + name);
                    Class s = c.getSuperclass();
                    if (s != null) {
                        String parent = s.getName();
                        if (parent != null && 
                            parent.equals("filters.Filter")) {
                            commandPanel.addToHistory(name);
                        }
                    }
                } catch (ClassNotFoundException e) {
                }
            }
        }
    }