patchNumComboBox.setEnabled(driver.isSingleDriver()
patchNumComboBox.setEnabled(driver != null && driver.isSingleDriver()
        public void actionPerformed (ActionEvent evt) {            IPatchDriver driver = (IPatchDriver)driverComboBox.getSelectedItem();            bankComboBox.removeAllItems();            patchNumComboBox.removeAllItems();            if (driver != null) {		String[] bankNumbers = driver.getBankNumbers();                if (bankNumbers != null && bankNumbers.length > 1) {                    for (int i = 0 ; i < bankNumbers.length ; i++) {            	        bankComboBox.addItem(bankNumbers[i]);                    }                }                if (driver.isSingleDriver()) {                    String[] patchNumbers = getPatchNumbers((ISingleDriver) driver);                    if (patchNumbers.length > 1) {                        for (int i = 0; i < patchNumbers.length; i++) {                            patchNumComboBox.addItem(patchNumbers[i]);                        }                        patchNumComboBox.setSelectedIndex(Math.min(patchNum,                                patchNumComboBox.getItemCount() - 1));                    }                }            }            bankComboBox.setEnabled(bankComboBox.getItemCount() > 1);            // N.B. Do not enable patch selection for banks            patchNumComboBox.setEnabled(driver.isSingleDriver()                    && patchNumComboBox.getItemCount() > 1);        }