allow qt4.6 with a warning

aqt/__init__.py

@@ -198,9 +198,10 @@ environment points to a valid, writable folder.""")
 
     # qt version must be up to date
     if qtmajor <= 4 and qtminor <= 6:
-        QMessageBox.critical(
-            None, "Error", "Anki requires Qt4.7 or later.")
-        return
+        QMessageBox.warning(
+            None, "Error", "Your Qt version is known to be buggy. Until you "
+          "upgrade to a newer Qt, you may experience issues such as images "
+          "failing to show up during review.")
 
     # parse args
     opts, args = parseArgs(sys.argv)