Comment 1 for bug 1178767

Looks like adding iterator access to GL3Slots fixes this:

pygl3display/infrastructure.py:

class GL3Slots(object):
    def __init__(self, slots, indices):
        self.slots = tuple(slots)
        self.indices = indices

    def release(self):
        self.indices.release(self.slots)

    def upload(self, data):
        self.indices.upload(self.slots, data)

+ def __iter__(self):
+ return self.slots.__iter__()