Graph: options for depth colours and dot sizes

Backend/Settings.py

@@ -53,6 +53,10 @@ DefaultSettings: dict[str, Any] = {
     # other one opens a dot).
     "GraphShowDirectories": True,
     "GraphPanButton": "Right",
+    # Directory dots: heading colours by depth (off: all Purple), and smaller
+    # the deeper they are.
+    "GraphColourByDepth": True,
+    "GraphShrinkByDepth": False,
 }
 
 DefaultThemesDirectory = ApplicationDirectory / "DefaultThemes"