bpo-38439: Add 256px IDLE icon (GH-17473)

Icon author: Andrew Clover, bpo-1490384

Lib/idlelib/Icons/README.txt

@@ -0,0 +1,9 @@
+The IDLE icons are from https://bugs.python.org/issue1490384
+
+Created by Andrew Clover.
+
+The original sources are available from Andrew's website:
+https://www.doxdesk.com/software/py/pyicons.html
+
+Various different formats and sizes are available at this GitHub Pull Request:
+https://github.com/python/cpython/pull/17473

Lib/idlelib/pyshell.py

@@ -1485,9 +1485,14 @@ def main():
         iconfile = os.path.join(icondir, 'idle.ico')
         root.wm_iconbitmap(default=iconfile)
     elif not macosx.isAquaTk():
-        ext = '.png' if TkVersion >= 8.6 else '.gif'
+        if TkVersion >= 8.6:
+            ext = '.png'
+            sizes = (16, 32, 48, 256)
+        else:
+            ext = '.gif'
+            sizes = (16, 32, 48)
         iconfiles = [os.path.join(icondir, 'idle_%d%s' % (size, ext))
-                     for size in (16, 32, 48)]
+                     for size in sizes]
         icons = [PhotoImage(master=root, file=iconfile)
                  for iconfile in iconfiles]
         root.wm_iconphoto(True, *icons)

Misc/NEWS.d/next/IDLE/2019-12-05-14-20-53.bpo-38439.j_L2PI.rst

@@ -0,0 +1,2 @@
+Add a 256×256 pixel IDLE icon to support more modern environments. Created by Andrew Clover.
+Delete the unused macOS idle.icns icon file.

PCbuild/lib.pyproj

@@ -1585,6 +1585,7 @@
     <Content Include="idlelib\Icons\idle_32.png" />
     <Content Include="idlelib\Icons\idle_48.gif" />
     <Content Include="idlelib\Icons\idle_48.png" />
+    <Content Include="idlelib\Icons\idle_256.png" />
     <Content Include="idlelib\Icons\minusnode.gif" />
     <Content Include="idlelib\Icons\openfolder.gif" />
     <Content Include="idlelib\Icons\plusnode.gif" />