Add docstrings. Also add safe_cast function. Finally

fix some minor issues.

double_text_button.py

@@ -2,11 +2,18 @@ from PyQt5.QtWidgets import QPushButton
 from PyQt5.QtCore import pyqtSlot
 
 class DoubleTextButton(QPushButton):
+    """Subclass QPushButton.
+
+    A click will deactivate/activate a series of 'slave' widgets depending
+    on the 'checked' status of the button."""
+
     def __init__(self, parent=None):
+        """Extends QPushButton.__init__."""
         super().__init__(parent)
         self.clicked.connect(self.__manage_click)
 
     def set_texts(self, text_a, text_b):
+        """Set the two texts to be displayed."""
         self.__text_a = text_a
         self.__text_b = text_b
 
@@ -15,6 +22,14 @@ class DoubleTextButton(QPushButton):
                           ruled_by_radio_1=None,
                           radio_2=None,
                           ruled_by_radio_2=None):
+        """Set all the 'slave' widgets.
+
+        Keyword arguments:
+        simple_ones -- a list of widgets.
+        radio_1 -- a radio button.
+        ruled_by_radio_1 -- a list of widgets whose status depend upon radio_1.
+        radio_2 -- a radio button.
+        ruled_by_radio_2 -- a list of widgets whose status depend upon radio_2."""
         self.__simple_ones = simple_ones
         self.__ruled_by_radio_1 = ruled_by_radio_1
         self.__radio_1 = radio_1
@@ -23,6 +38,7 @@ class DoubleTextButton(QPushButton):
 
     @pyqtSlot()
     def __manage_click(self):
+        """Set the status of all the 'slave widgets' based on the status of the instance."""
         if self.isChecked():
             self.setText(self.__text_b)
             enable = False