--- filediff.py 

+++ filediff.py.fixed

@@ -822,7 +822,11 @@

     def make_patch(self, pane):

         fontdesc = pango.FontDescription(self.prefs.get_current_font())

-        dialog = gnomeglade.Component( paths.share_dir("glade2/filediff.glade"), "patchdialog")

+        override = {}

+        if sourceview_available:

+            override["GtkTextView"] = gsv.SourceView

+            override["GtkTextBuffer"] = gsv.SourceBuffer

+        dialog = gnomeglade.Component( paths.share_dir("glade2/filediff.glade"), "patchdialog", override)

         dialog.widget.set_transient_for( self.widget.get_toplevel() )

         bufs = [t.get_buffer() for t in self.textview]

         texts = [b.get_text(*b.get_bounds()).split("\n") for b in bufs]

@@ -833,12 +837,20 @@

         try: prefixslash = prefix.rindex("/") + 1

         except ValueError: prefixslash = 0

         names = [n[prefixslash:] for n in names]

+        if sourceview_available:

+            dialog.textview.set_buffer( gsv.SourceBuffer() )

         dialog.textview.modify_font(fontdesc)

         buf = dialog.textview.get_buffer()

         lines = []

         for line in difflib.unified_diff(texts[0], texts[1], names[0], names[1]):

             buf.insert( buf.get_end_iter(), line )

             lines.append(line)

+        if sourceview_available:

+            man = gsv.SourceLanguagesManager()

+            gsl = man.get_language_from_mime_type("text/x-diff")

+            if gsl:

+                buf.set_language(gsl)

+                buf.set_highlight(True)

         result = dialog.widget.run()

         dialog.widget.destroy()

         if result >= 0: