[meld] meldbuffer: Fix tag applying on paste (bgo#709580)

[Kai Willadsen <kaiw src gnome org>]

commit ef124355cef3a8e6ac93cf1200b15c0892ccdbe7
Author: Kai Willadsen <kai willadsen gmail com>
Date:   Sun Feb 9 08:51:35 2014 +1000

    meldbuffer: Fix tag applying on paste (bgo#709580)
    
    This is just a horrible hack around GtkTextBuffer's limited hooks for
    dealing with clipboard stuff.

 meld/meldbuffer.py |   20 ++++++++++++++++++++
 1 files changed, 20 insertions(+), 0 deletions(-)
---
diff --git a/meld/meldbuffer.py b/meld/meldbuffer.py
index 74aaa67..8959877 100644
--- a/meld/meldbuffer.py
+++ b/meld/meldbuffer.py
@@ -34,6 +34,26 @@ class MeldBuffer(GtkSource.Buffer):
     def __init__(self, filename=None):
         GtkSource.Buffer.__init__(self)
         self.data = MeldBufferData(filename)
+        self.user_action_count = 0
+
+    def do_begin_user_action(self, *args):
+        self.user_action_count += 1
+
+    def do_end_user_action(self, *args):
+        self.user_action_count -= 1
+
+    def do_apply_tag(self, tag, start, end):
+        # Filthy, evil, horrible hack. What we're doing here is trying to
+        # figure out if a tag apply has come from a paste action, in which
+        # case GtkTextBuffer will 'helpfully' apply the existing tags in the
+        # copied selection. There appears to be no way to override this
+        # behaviour, or to hook in to the necessary paste mechanics to just
+        # request that we only get plain text or something. We're abusing the
+        # user_action notion here, because we only apply the tags we actually
+        # want in a callback.
+        if tag.props.name == 'inline' and self.user_action_count > 0:
+            return
+        return GtkSource.Buffer.do_apply_tag(self, tag, start, end)
 
     def reset_buffer(self, filename):
         """Clear the contents of the buffer and reset its metadata"""