private void RightButtonActionPerformed(java.awt.event.ActionEvent evt) {//GEN-FIRST:event_RightButtonActionPerformed
        if (FocusOwnerIndex == 1) {
            if (NumberField1.getCaretPosition() >= NumberField1.getText().length()) { // jump to next textfield
                FocusOwnerIndex += 1;
                NumberField2.requestFocus();
                NumberField2.setCaretPosition(0); // before first character
            } else {
                NumberField1.setCaretPosition(NumberField1.getCaretPosition() + 1);
                NumberField1.getCaret().setVisible(true);
            }
        } else if (FocusOwnerIndex == 2) {
            if (NumberField2.getCaretPosition() >= NumberField2.getText().length()) { // jump to next textfield
                FocusOwnerIndex += 1;
                NumberField3.requestFocus();
                NumberField3.setCaretPosition(0); // before first character
            } else {
                NumberField2.setCaretPosition(NumberField2.getCaretPosition() + 1);
                NumberField2.getCaret().setVisible(true);
            }
        } else if (FocusOwnerIndex == 3) {
            if (NumberField3.getCaretPosition() >= NumberField3.getText().length()) { // jump to next textfield
                FocusOwnerIndex += 1;
                NumberField4.requestFocus();
                NumberField4.setCaretPosition(0); // before first character
            } else {
                NumberField3.setCaretPosition(NumberField3.getCaretPosition() + 1);
                NumberField3.getCaret().setVisible(true);
            }
        } else if (FocusOwnerIndex == 4) {
            if (NumberField4.getCaretPosition() >= NumberField4.getText().length()) { // do nothing
            } else {
                NumberField4.setCaretPosition(NumberField4.getCaretPosition() + 1);
                NumberField4.getCaret().setVisible(true);
            }
        }
    }//GEN-LAST:event_RightButtonActionPerformed