Cool. Rated 4 out of 5 stars

Works for me right fine! Just install and go.

I had only two small improvement ideas:
- Make the QR code somehow being able to copy&paste for transferring it electronically.
- For really large meetings (having lots of descriptions and attendees) either the screen or the mobile camera resolution was not enough to scan the QRC. I don't know if some sort of full screen or zoom would have helped?

This review is for a previous version of the add-on (1.1.0). 

Thanks for your review.

Regarding copy & paste: Nice idea, I'll think about it. The tooltip will go away whenever you press a key though, so I need to think about alternatives. Maybe auto-copying the GIF image to the clipboard after a configurable timeout or copying it via an entry in the context-menu of the event would do...

As for the second issue, here are some aspects to consider:
- First, the more data there is to encode, the more detailed and harder to scan the QR code will be. This is further influenced by technical limitations, like screen and camera size/resolution and environment variables like lighting conditions. Therefore, if there is any way to reduce the amount of data to encode, this is the most effective way for improvement.
- I've had problems with "big" events, too, though most codes work fine. How much data do those events contain, can you provide more information about hardware, etc.? If you turn on logging and bring up the error console, you will see how many characters need to be encoded. It should be possible to copy the data out of there and paste it into another QR code generator for testing purposes.
- In my experience, enlarging the QR code in most cases will not help, as this just forces you to hold the phone further away from the screen for the code to fit into the scan area. So if the resolution is the limiting factor, there's not much you can do about it. You can verify that by testing other generators on the web. Yet, if you find out then that it gets better, please tell me.
- Resizing can blur the image, making recognition even harder.
- I've tried to make the QR codes always have a roughly similar size in pixels so that they go well with the tooltips, and to save screen space. Maybe I can fine-tune these settings.
- Though propably not a typical use-case for most people, I can imagine one scenario for full-screen/zoomed QR codes: Sharing an event during a presentation (projector). Currently, I do not have plans to support this, but if I implement copy & paste, then you could transfer the code to your presentation document and resize it there.

Edit: Ok. I've created VERY large events that need QR code version > 35 (more than 2303 characters), and I see that this is in fact too small to be recognizable. This will be fixed in the next version.