Menu is opened at the wrong position when Enter key is pressed
In your demo (index.html), if you set the focus on the "Click this button" button (without clicking it) and hit Enter, the menu is opened at a wrong position. Maybe check if a key is pressed and then use event.target to determine the source element.
Thanks for reporting, I'm on it. It seems like we didn't get the position calculation based on elements quite right in the position update, so it might be a bit more complicated. (event based position calculation works fine though) If you have this issue yourself, you could probably fix it in the meantime by adding a keypress handler and opening the menu manually...
Well, I don't open the menu by mouse position myself but I thought I report it anyway.
Let's close this for now. I will let you to decide whether to fix it or not,