Merge pull request #75 from mwcraig/better-qt-error

qt fails on python 3.8 and up, so raise a better error message

Author: mwcraig

vpython/no_notebook.py

@@ -249,6 +249,10 @@ def onClose(self, wasClean, code, reason):
         raise RuntimeError('The pyqt browser cannot be used on Windows. '
                            'Please use the default browser instead by '
                            'removing set_browser("pyqt") from your code.')
+    elif sys.version_info.major == 3 and sys.version_info.minor >= 7:
+        raise RuntimeError('The pyqt browser cannot be used on Python 3.8. '
+                           'Please use the default browser instead by '
+                           'removing set_browser("pyqt") from your code.')
 
 
 def start_Qapp(port):