Merge pull request #6078 from radarhere/imageshow

Author: hugovk

docs/reference/ImageShow.rst

@@ -23,6 +23,9 @@ All default viewers convert the image to be shown to PNG format.
     .. autoclass:: PIL.ImageShow.EogViewer
     .. autoclass:: PIL.ImageShow.XVViewer
 
+    To provide maximum functionality on Unix-based systems, temporary files created
+    from images will not be automatically removed by Pillow.
+
 .. autofunction:: PIL.ImageShow.register
 .. autoclass:: PIL.ImageShow.Viewer
     :member-order: bysource

src/PIL/ImageShow.py

@@ -25,7 +25,12 @@
 
 def register(viewer, order=1):
     """
-    The :py:func:`register` function is used to register additional viewers.
+    The :py:func:`register` function is used to register additional viewers::
+
+        from PIL import ImageShow
+        ImageShow.register(MyViewer())  # MyViewer will be used as a last resort
+        ImageShow.register(MySecondViewer(), 0)  # MySecondViewer will be prioritised
+        ImageShow.register(ImageShow.XVViewer(), 0)  # XVViewer will be prioritised
 
     :param viewer: The viewer to be registered.
     :param order: