simplified no Tk() sets _default_root

Demo/tkinter/guido/imageview.py

@@ -4,9 +4,8 @@ import sys
 def main():
     filename = sys.argv[1]
     root = Tk()
-    label = Label(root)
     img = PhotoImage(file=filename)
-    label['image'] = img
+    label = Label(root, image=img)
     label.pack()
     root.mainloop()