static void setTheme(String theme) {

        try {
            for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
                if (theme.equals(info.getName())) {
                    javax.swing.UIManager.setLookAndFeel(info.getClassName());
                    break;  
                }
            }

        } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
            Logger.getLogger(SolverGUI.class.getName()).log(Level.SEVERE, null, ex);
        }

        gui.setVisible(false);
        gui = new SolverGUI();
        gui.setVisible(true);

        if (about.isVisible()) {
            about.setVisible(false);
            about = new About();
            about.setVisible(true);
        } else {
            about = new About();
        }

    }