code: def open_file_dialog(self):
          
          dialog = QtWidgets.QFileDialog
          sender = self.sender()
          if sender == self.btn_open_source:
              textbox = self.source_path
          elif sender == self.btn_open_target:
              textbox = self.target_path
          folder = dialog.getExistingDirectory(self, 'Select a file:', textbox.text(), options = QtWidgets.QFileDialog.ShowDirsOnly)
          if str(folder) != '':
              textbox.setText(folder)
              # load elements from file and display in tree
              if sender == self.btn_open_source:
                  self.reset_avaliable(folder)
docs: Opens a file dialog to get the path to a file and put tha tpath in the correct textbox