io: Apply double extensions workaround for Windows too

Author: lanzagar

Orange/data/io.py

@@ -297,12 +297,14 @@ def __new__(cls, name, bases, attrs):
             for compression in Compression.all:
                 for ext in newcls.EXTENSIONS:
                     new_extensions.append(ext + compression)
-                # OSX file dialog doesn't support filtering on double
-                # extensions (e.g. .csv.gz)
-                # https://bugreports.qt.io/browse/QTBUG-38303
-                # This is just here for OWFile that gets QFileDialog
-                # filters from FileFormat.readers.keys()
-                if sys.platform == 'darwin':
+                if sys.platform in ('darwin', 'win32'):
+                    # OSX file dialog doesn't support filtering on double
+                    # extensions (e.g. .csv.gz)
+                    # https://bugreports.qt.io/browse/QTBUG-38303
+                    # This is just here for OWFile that gets QFileDialog
+                    # filters from FileFormat.readers.keys()
+                    # EDIT: Windows exhibit similar problems:
+                    # while .tab.gz works, .tab.xz and .tab.bz2 do not!
                     new_extensions.append(compression)
             newcls.EXTENSIONS = tuple(new_extensions)