Add extension to files that come into the clipboard without one.

sugar/objects/mime.py

@@ -9,3 +9,21 @@ def get_for_file(file_name):
         
 def get_from_file_name(file_name):
     return _sugarext.get_mime_type_from_file_name(file_name)
+
+_extensions_cache = {}
+def get_primary_extension(mime_type):
+    if _extensions_cache.has_key(mime_type):
+        return _extensions_cache[mime_type]
+
+    f = open('/etc/mime.types')
+    while True:
+        line = f.readline()
+        cols = line.replace('\t', ' ').split(' ')
+        if mime_type == cols[0]:
+            for col in cols[1:]:
+                if col:
+                    _extensions_cache[mime_type] = col
+                    return col
+
+    _extensions_cache[mime_type] = None
+    return None