Add docstrings. Also add safe_cast function. Finally

fix some minor issues.

fixed_aspect_ratio_widget.py

@@ -3,12 +3,16 @@ from PyQt5.QtCore import QSize
 
 
 class FixedAspectRatioWidget(QWidget):
+    """Subclass QWidget. Keep all the internal labels to a fixed aaspect ratio."""
+
     space = 10
     def __init__(self, parent=None):
+        """Initialize the instance."""
         super().__init__(parent)
         self.labels = []
 
     def resizeEvent(self, event):
+        """Override QWidget.resizeEvent. Rescale all the internal widgets."""
         h, w = self.height(), self.width()
         h_lbl = h / 9 - self.space
         w_lbl = 5 * h_lbl