Dont use win32com for notifying the OS of file association changes

src/calibre/utils/windows/wintest.py

@@ -30,6 +30,9 @@ class TestWinutil(unittest.TestCase):
     def test_special_folder_path(self):
         self.assertEqual(os.path.expanduser('~'), self.winutil.special_folder_path(self.winutil.CSIDL_PROFILE))
 
+    def test_associations_changed(self):
+        self.assertIsNone(self.winutil.notify_associations_changed())
+
 
 def find_tests():
     return unittest.defaultTestLoader.loadTestsFromTestCase(TestWinutil)

src/calibre/utils/windows/winutil.c

@@ -377,6 +377,7 @@ winutil_strftime(PyObject *self, PyObject *args)
 static char winutil_doc[] = "Defines utility methods to interface with windows.";
 extern PyObject *add_to_recent_docs(PyObject *self, PyObject *args);
 extern PyObject *file_association(PyObject *self, PyObject *args);
+extern PyObject *notify_associations_changed(PyObject *self, PyObject *args);
 
 static PyMethodDef winutil_methods[] = {
     {"special_folder_path", winutil_folder_path, METH_VARARGS,
@@ -452,6 +453,10 @@ be a unicode string. Returns unicode strings."
         "file_association()\n\nGet the executable associated with the given file extension"
     },
 
+    {"notify_associations_changed", (PyCFunction)notify_associations_changed, METH_VARARGS,
+        "notify_associations_changed()\n\nNotify the OS that file associations have changed"
+    },
+
     {NULL, NULL, 0, NULL}
 };
 

src/calibre/utils/windows/winutilpp.cpp

@@ -72,4 +72,10 @@ file_association(PyObject *self, PyObject *args) {
 	return Py_BuildValue("u#", buf, (int)sz);
 }
 
+PyObject *
+notify_associations_changed(PyObject *self, PyObject *args) {
+	SHChangeNotify(SHCNE_ASSOCCHANGED, SHCNF_DWORD | SHCNF_FLUSH, NULL, NULL);
+	Py_RETURN_NONE;
+}
+
 }

src/calibre/utils/winreg/default_programs.py

@@ -12,7 +12,7 @@ from threading import Thread
 import winerror
 
 from calibre import guess_type, prints
-from calibre.constants import is64bit, isportable, isfrozen, __version__, DEBUG
+from calibre.constants import is64bit, isportable, isfrozen, __version__, DEBUG, plugins
 from calibre.utils.winreg.lib import Key, HKEY_CURRENT_USER, HKEY_LOCAL_MACHINE
 from polyglot.builtins import iteritems, itervalues
 
@@ -131,8 +131,8 @@ def register():
         with Key(r'Software\RegisteredApplications') as key:
             key.set(data['name'], capabilities_path)
 
-    from win32com.shell import shell, shellcon
+    winutil = plugins['winutil'][0]
-    shell.SHChangeNotify(shellcon.SHCNE_ASSOCCHANGED, shellcon.SHCNF_DWORD | shellcon.SHCNF_FLUSH, 0, 0)
+    winutil.notify_associations_changed()
 
 
 def unregister():