import sys

 from PyQt5.QtWidgets import *

 from PyQt5.QtCore import Qt, pyqtSignal

 class FindDialog(QDialog):

     findNext = pyqtSignal(str, Qt.CaseSensitivity)

     findPrevious = pyqtSignal(str, Qt.CaseSensitivity)

     def __init__(self, parent = None):

         super().__init__(parent)

         self.label = QLabel(self.tr("Find &what:"))

         self.lineEdit = QLineEdit()

         self.label.setBuddy(self.lineEdit)

         self.caseCheckBox = QCheckBox(self.tr("Match &case"))

         self.backwardCheckBox = QCheckBox(self.tr("Search &backward"))

         self.findButton = QPushButton(self.tr("&Find"))

         self.findButton.setDefault(True)

         self.findButton.setEnabled(False)

         self.closeButton = QPushButton(self.tr("Close"))

         self.lineEdit.textChanged.connect(self.enableFindButton)

         self.findButton.clicked.connect(self.findClicked)

         self.closeButton.clicked.connect(self.close)

         self.topLeftLayout = QHBoxLayout()

         self.topLeftLayout.addWidget(self.label)

         self.topLeftLayout.addWidget(self.lineEdit)

         self.leftLayout = QVBoxLayout()

         self.leftLayout.addLayout(self.topLeftLayout)

         self.leftLayout.addWidget(self.caseCheckBox)

         self.leftLayout.addWidget(self.backwardCheckBox)

         self.rightLayout = QVBoxLayout()

         self.rightLayout.addWidget(self.findButton)

         self.rightLayout.addWidget(self.closeButton)

         self.rightLayout.addStretch()

         self.mainLayout = QHBoxLayout()

         self.mainLayout.addLayout(self.leftLayout)

         self.mainLayout.addLayout(self.rightLayout)

         self.setLayout(self.mainLayout)

         self.setWindowTitle(self.tr("Find"))

         self.setFixedHeight(self.sizeHint().height())

     def findClicked(self):

         text = self.lineEdit.text()

         cs = (Qt.CaseSensitive if self.caseCheckBox.isChecked()

               else Qt.CaseInsensitive)

         if self.backwardCheckBox.isChecked():

             self.findPrevious.emit(text, cs)

         else:

             self.findNext.emit(text, cs)

     def enableFindButton(self, text):

         self.findButton.setEnabled(not text == '')

 if __name__ == '__main__':

     app = QApplication(sys.argv)

     dialog = FindDialog()

     dialog.show()

     sys.exit(app.exec())