diff -r 94a5bf416e50 Lib/idlelib/PyShell.py
--- a/Lib/idlelib/PyShell.py	Tue May 29 22:55:43 2012 -0700
+++ b/Lib/idlelib/PyShell.py	Thu May 31 11:01:36 2012 -0500
@@ -309,6 +309,11 @@
             "console": idleConf.GetHighlight(theme, "console"),
         })
 
+    def removecolors(self):
+        # Don't remove shell color tags before "iomark"
+        for tag in self.tagdefs:
+            self.tag_remove(tag, "iomark", "end")
+
 class ModifiedUndoDelegator(UndoDelegator):
     "Extend base class: forbid insert/delete before the I/O mark"
 
diff -r 94a5bf416e50 Misc/NEWS
--- a/Misc/NEWS	Tue May 29 22:55:43 2012 -0700
+++ b/Misc/NEWS	Thu May 31 11:01:36 2012 -0500
@@ -10,6 +10,8 @@
 Core and Builtins
 -----------------
 
+- Issue #14962: Preserve IDLE shell coloring tags when changing configuration.
+
 - Issue #14835: Make plistlib output empty arrays & dicts like OS X.
   Patch by Sidney San Martín.