Update canvas width and height when window changes.

I don't know why Tk(inter) doesn't do this?

ui.py

@@ -102,7 +102,10 @@ class App:
         notebook.pack(expand=True, fill=BOTH)
 
     def handle_canvas_resize(self, event):
-        print(event)
+        # I don't know why the Tk system doesn't update these values.
+        self.canvas['width'] = event.width
+        self.canvas['height'] = event.height
+        # print(event)
 
     def update_star_system_tab(self, name, x, y):
         self.star_name_label['text'] = name