Bug: Write Protected Files - Weird Error Message

Hello MyPaint Team,

I found a little bug in MyPaint. You can reproduce it with the following steps:

  1. Apply the “read only” protection flag to an “.ora”-file of your choice by using the Windows Explorer.
  2. Open the protected file with MyPaint.
  3. You cannot save to that file, as intended, but MyPaint unfortunately raises a weird error message, if you try to save. I translated it into English for you. It says: “A programming error has been detected.”

I just want to let you know…

The about box of my installation shows the following version information:
MyPaint w64
(Python 2.7.13, GTK 3.22.7, GdkPixbuf 2.36.4, Cairo 1.15.4, GLib 2.50.1)
Im using Windows 10.