--- a/mercurial/ui.py	Fri Mar 11 10:30:08 2016 +0000
+++ b/mercurial/ui.py	Mon Mar 14 15:01:27 2016 +0000
@@ -697,6 +697,77 @@
             return False
         return util.isatty(fh)
 
+    def interface(self, feature):
+        """what interface to use for interactive console features?
+
+        The interface is controlled by the value of `ui.interface` but also by
+        the value of feature-specific configuration. For example:
+
+        ui.interface.histedit = text
+        ui.interface.chunkselector = curses
+
+        Here the features are "histedit" and "chunkselector".
+
+        The configuration above means that the default interfaces for commands
+        is curses, the interface for histedit is text and the interface for
+        selecting chunk is crecord (the best curses interface available).
+
+        Consider the following exemple:
+        ui.interface = curses
+        ui.interface.histedit = text
+
+        Then histedit will use the text interface and chunkselector will use
+        the default curses interface (crecord at the moment).
+        """
+        alldefaults = frozenset(["text", "curses"])
+
+        featureinterfaces = {
+            "chunkselector": [
+                "text",
+                "curses",
+            ]
+        }
+
+        # Feature-specific interface
+        if feature not in featureinterfaces.keys():
+            # Programming error, not user error
+            raise ValueError("Unknown feature requested %s" % feature)
+
+        availableinterfaces = frozenset(featureinterfaces[feature])
+        if alldefaults > availableinterfaces:
+            # Programming error, not user error. We need a use case to
+            # define the right thing to do here.
+            raise ValueError(
+                "Feature %s does not handle all default interfaces" %
+                feature)
+
+        if self.plain():
+            return "text"
+
+        # Default interface for all the features
+        defaultinterface = "text"
+        i = self.config("ui", "interface", None)
+        if i in alldefaults:
+            defaultinterface = i
+
+        choseninterface = defaultinterface
+        f = self.config("ui", "interface.%s" % feature, None)
+        if f in availableinterfaces:
+            choseninterface = f
+
+        if i is not None and defaultinterface != i:
+            if f is not None:
+                self.warn(_("invalid value for ui.interface: %s\n") %
+                          (i,))
+            else:
+                self.warn(_("invalid value for ui.interface: %s (using %s)\n") %
+                         (i, choseninterface))
+        if f is not None and choseninterface != f:
+            self.warn(_("invalid value for ui.interface.%s: %s (using %s)\n") %
+                      (feature, f, choseninterface))
+
+        return choseninterface
+
     def interactive(self):
         '''is interactive input allowed?