replaceButton.addActionListener(this);
replaceAllButton.addActionListener(this);
nextEnabler = new NonemptyTextFieldButtonEnabler(nextButton);
nextEnabler.addRequiredField(findBox);
new NonemptyTextFieldActionEnabler(FIND_NEXT_ACTION).addRequiredField(findBox);
prevEnabler = new NonemptyTextFieldButtonEnabler(prevButton);
prevEnabler.addRequiredField(findBox);
replaceEnabler = new NonemptyTextFieldButtonEnabler(replaceAndFindButton);
replaceEnabler.addRequiredField(findBox);
replaceAndFindEnabler = new NonemptyTextFieldButtonEnabler(replaceButton);