Clear clipboard after closing window.

prog/tqr.py

@@ -27,7 +27,12 @@ def main():
     root = tk.Tk()
     root.title = "Qr code"
     root.state("iconic")
+    try:
         data = root.clipboard_get()
+    except Exception as e:
+        messagebox.showerror("Qr code", f"Cannot get content of clipboard.\n«{e}»")
+        exit(1)
+
     try:
         code = qr.create(data)
     except ValueError as e:
@@ -47,6 +52,13 @@ def main():
     img.config(background="white")
     label = tk.Label(root, image=img)
     label.pack()
+
+    def empty_clipboard():
+        root.clipboard_clear()
+        root.destroy()
+
+    root.protocol("WM_DELETE_WINDOW", empty_clipboard)
+
     root.mainloop()