Fix: positional argument specifiers are required by Python 2.6

cgohlke · cgohlke · commit 56fe6b2e8f18 · 2012-12-11T23:18:44.000-08:00
diff --git a/lib/matplotlib/backends/backend_gtk.py b/lib/matplotlib/backends/backend_gtk.py
@@ -341,7 +341,7 @@ def _get_key(self, event):
                                  [gdk.MOD1_MASK, 'alt'],
                                  [gdk.CONTROL_MASK, 'ctrl'],):
             if event.state & key_mask:
-                key = '{}+{}'.format(prefix, key)
+                key = '{0}+{1}'.format(prefix, key)
 
         return key
 
