private void btn_largerActionPerformed(java.awt.event.ActionEvent evt) {//GEN-FIRST:event_btn_largerActionPerformed
        if (getFontSize() < 40) {
            setFontSize(fontSize + 2);
            
            lbl_display.setFont(new Font(lbl_display.getFont().getFamily(),
                0, getFontSize()));
        } else {
            JOptionPane.showMessageDialog(null, "Too large!",
                    "Error", JOptionPane.ERROR_MESSAGE);
        }
        
        displayCurrentFontSize();
    }//GEN-LAST:event_btn_largerActionPerformed